I've made a few minor edits throughout to fix typos, remove some ambiguity, and to adjust formatting.

Lead

• Y

Early life

• Y

Career

• Y

Projects

• Please can you attribute the following quotes:
  •  Done The latter made the designer "a true architectural pioneer."
  •  Done making this "an early and excellent example of a multi-use project."
  •  Done It "has been hailed as one of the finest examples of Romanesque Revival architecture in New York City."
  •  Done At the time, this "fortress-like mansion" was quite different from the Queen Anne style that was popular in New Haven.
•  Done The quotation from George Brush about North Sheffield is a bit out of proportion compared to the rest of the subsection (i.e. it is a large quotation about only one of the many buildings). Is it necessary to include? Comment: Good question. I realized that an overview of the styles that Cady used at Yale was needed, not just a list and a description of one building. Sources were slim on the demolished buildings, but I added some descriptions and split the long list of buildings, which should read better. I left the quote, shortened a bit, with a new intro that explains that this description applies to three buildings (one that survives). I can trim the quote some more, if you think that is needed but think it makes sense now.

Professional affiliations

• Y

Honours

• Y

Personal

• Y

Lead sections

•  Done I don't think you need to state "or J. Cleaveland Cady" in the lead. See MOS:FULLNAME.
•  Done "Rundbogenstil style" is mentioned in the lead but never again in the article - I suggest removing.
•  Done More than fifteen of Cady's buildings are listed in the National Register of Historic Places. Only 12 NRHPs are listed in the table in the article. Is there another source stating that there are over fifteen? If not, I'd suggest changing the detail in the lead.
•  Done In 1920, Alexander Dana Noyes wrote, "In his professional career, J. Cleveland Cady was perhaps the embodiment of the effort of American architecture, fifty years ago, to find itself while cutting loose from the false and meretricious standards of the Second Empire." The lead should only contain info included in the rest of the article, so this standalone quotation feels out of place. It would sit far better within the article body.
•  Done His best-known surviving design is the American Museum of Natural History in New York City, although his contemporaries knew him for the Metropolitan Opera House and fifteen buildings at Yale University, now demolished. Is there anything which can back up the statement that the American Museum of Natural History is the "best-known" surviving design? Or the statement that he was more famous during his lifetime for other things? Comment: There was at one point, but this must have been cut. I reworded it to solve the issue.

Layout

•  Done I don't think a 'Professional affiliations' section is needed, as it only mentioned one professional affiliation. Could you move the paragraphs into the 'Career' section instead?
•  Done Similarly 'Honours' could be a subheading of 'Career', as it is quite a short section by itself.
•  Done 'Personal' is usually called 'Personal life'.

Words to watch

• None idenitifed.

Fiction

• Y

List incorporation

•  Done The list in the Honours section could probably work as prose, but I don't think it's an issue if it stays as a list.

• Sources of information are cited in the appropriate places.

Source spot-check

The New York Times. 1919-04-18

•  Done Cady and Gregory formed a partnership known as Cady & Gregory in 1909. I can't find this in the source. You may want to cite Curran, Kathleen (1993) p.4 instead. Comment: Good catch. Obviously, there was another source at some point.
•  Done In 1881, he married Emma Matilda Bulkley of Orange, New Jersey. I know there's only so many ways of saying this fact, but this sentence is exactly the same as that in the source, so I'd suggest changing.

Curran, Kathleen (1993).

•  Done Between 1857 and 1864, Cady pursued his studies in architecture with an unknown German professor of architecture who was living in New York City. I don't think the source explicitly states that the professor lived in NYC, only that Cady probably studied in NYC, and that separately he was tutored by a German professor. It could be that the professor was no tin NYC.
•  Done With formal training in Germany, Berg was the structural and mechanical engineer for the firm.
  •  Done The source states that Berg also had training in Prussia and Switzerland.
  •  Done The source states that Berg was probably the structural and mechanical engineer - it is not certain, so I'd suggest changing the article to change this.
•  Done In 1869, Cady received his big break with the commission to build the Brooklyn Art Association's Brooklyn Academy of Design. The reference to "big break" is a bit peacock-y and too close to what is in the source, so I'd suggest changing this sentence.
• Strikethrough Done inexpensive construction costs, functionality, and fireproofing. This is being very picky, but I can't help but think this is paraphrasing the source too closely. For the avoidance of doubt, I'd suggest changing.
•  Done Cady's design departed "from the traditional 'tomb-like' structures of fraternities at other schools." Instead, his Romanesque fraternity house "was more a cross between a house and fortress." it is Cady's "most overtly Richardsonian building." This became "one of the most successful and well-publicized public baths in nineteenth-century America." Can you attribute these quotes to Curran?
•  Done In 1883, Cady designed the Morgan Hall dormitory for Williams Collage. This was followed by a Lasell Gymnasium in 1886. Both buildings are a mix of Romanesque and Dutch styles and were executed in Kentucky and Williamstown limestone. I think these are meant to be p.37. Comment: Thanks for finding this error. I added the page numbers later, for the GA review, and obviously did not get them all right.
•  Done it was to include eighty showers. I can't find this on p.40. Comment: Source said eighty baths, most with rain showers. I correct the text.

New York City Landmarks Preservation Commission. 1988.

•  Done Although this is not the style Cady is known for, architect Montgomery Schuyler said the Brooklyn Academy of Design is "one of the few successful secular Gothic designs." This is not a direct quote, so I'd rephrase and get rid of the quotation marks. Comment: I tracked down the original source of the quote

Brief Biographies of American Architects Who Died Between 1897 and 1947.

•  Done In 1871 Milton See (1854–1920) joined his practice, followed by Louis DeCoppet Berg (1856–1945) in 1873. I can see this info on p.20.

Harkrader, Nina E. (2021-07-01).

•  DoneCady was the architect of the original Metropolitan Opera House which opened in October 1883. I don't think the newspaper source states an opening date, and SAH Archipedia states it was completed in 1884. Comment: I found and restored the correct source. Also, newspaper articles confirm the fall 1883 opening season.
•  Done Designed by Cady, the Romanesque style Othniel C. Marsh House was built from 1875 to 1880 in New Haven. SAH Archipedia states it was opened in 1881. Comment: The other source mentions different completion dates for the interior and exterior. Since they both mention 1881, I am fine switching to that.
•  Done Marsh bequeathed the house to Yale University in 1899. This is almost exactly the same as the source, so I'd suggest changing.

Continuing spot-check

"J. Cleaveland Cady, Architect". Hartford Courant (Hartford, Connecticut).

• Y

Korom J. JJ.

•  Done The latter made the designer "a true architectural pioneer." Can you attribute this to Korom?
•  Done ..making this "an early and excellent example of a multi-use project." Same here.
•  Done However, in 1936, it was noted, "The opera house was designed by J. C. Cady... Could you attribute this quotation? There is a footnote in the source which should say. Comment: Because Korom's citation was unclear, I ended up tracking down the original source for the quote. Thanks for encouraging me to explore this.

Garbe, Patricia (February 1984).

•  Done In 1866, Cady designed the Nordhoff estate for Mr. and Mrs. Charles Nordhoff in Alpine, New Jersey. The source states that he visited Alpine in 1865 and designed the estate - there doesn't seem to be a mention of 1866?

Chicago Tribune. January 19, 1878.

• Y

"National Register Information System". National Register of Historic Places.

•  Done This source is repeated twice. The URL takes you to the search page. I'm guessing these citations are meant to link to the relevant entry? Comment: National Register citations are an ongoing battle across Wikipedia. Firstly, the NRHP keeps changing its website page names. Secondly, bots and editor's cleanup tools keep removing the specific search part of the citation, making the link redirect to the generic search page. I fixed the links and updated the citations to be different and to reflect the current name of the NRHP database website.

"Plate No. VIII". The New York Sketch-Book of Architecture.

•  Done As far as I can see, the source (pages 99 or 107) does not describe the building as "highly-ornate" - is this inferred from the image? If so I'd remove from the article as that's an opinion.
•  Done Similarly, is The client's name and the building location is unknown. just inferred from the fact that there are none listed in the source? If so, I'd remove from the article as that's teetering on an assumption.

J. Cleveland Cady". New York Herald.

• Y

"Boone Tavern Hotel". National Register of Historic Places.

•  Done I can't see a mention of Berea College in this source? Comment: It throughout the document. I added the specific quote from unnumbered p. 7 to the citation.

"The Brooklyn Academy of Design". The American Architect and Building News.

•  Done The citation should state pp.35 and 40 (not 37).

"First Presbyterian Church of Oyster Bay". National Register of Historic Places.

• Y

Plantsville Historic District National Register of Historic Places. National Park Service.

• Y

History of the First Presbyterian Church of Ithaca, New York, During One Hundred Years.

• Y

Sullebarger, Beth; Arms, Meredith (November 1987).

• Y

I've checked over 20% of sources including those which I have access to with the most citations, so I'm content to stop here.

Source reliability spot-check

"Yale's Lost Landmarks". Yale Alumni Magazine.

• Is this an official Yale publication?  Done Comment: It is the official publication of the Yale Alumni Association. The landing page for the start of the article is here

"Ladies' Hall / Fairchild Hall, Berea College, Chestnut and South Main Street, Berea, Kentucky". Placeography.

•  Done What makes this a reliable source? I had to access via the Wayback machine (link broken) but it looks like a Wiki. Comment: I have updated the citation to include the new link and its publisher, the Minnesota Historical Society. Unfortunately, Wayback did not capture the source page that goes with this article but the link to it remains as an indication that this was a credible resource with references.

"Boone Tavern History & Features". Historic Boone Tavern Hotel & Restaurant.

•  Done I had to access via the Wayback machine (link broken again). What makes this a reliable source? Generally I'd be hesitant to use historical information provided by an institution about itself - if there is a secondary source external to the Hotel (e.g. a book or news article) I'd much rather that was used.

Wessels, William. Trailmarker

•  Done Can I check what makes this a reliable source? It appears to be a self-published blog (not sure how to determine whether the author is an authority on the subject). Also the name of the website is not Trailmarker. Comment: Trailmaker was the magazine that originally published this article in 1962. The article is republished on the Church of the Good Shepherd's website. I have updated the citation to indicate this. Its author was one of two founders of the Adirondack Museum, president of the Adirondack Historical Association, and senior warden of one of the churches covered in the article. Note that the only time this citation is use, it is now paied with another source.

"First Presbyterian Church". Pocket Sights.

•  Done What makes this a reliable source? I'm unclear exactly what the website is and whether to trust the validity of info.  Done Comment: I replaced the source

"J. Cleveland Cady". Landmark Hunter.

•  Done I can't access this source unfortunately. What makes this a reliable source? Comment: I replace this source with the NRHP nomination form.

"Church of Good Shepherd: History". St. Huberts Isle.

•  Done Similar to above, ideally I wouldn't want to cite historical info about a place from a publication by the place itself (if that makes sense). If there's an alternate source that would be great.

"The Church of the Good Shepherd -- No. 152 West 66th Street". Daytonian in Manhattan.

•  Done This appears to be a blog, so not ideal for reliability.

"Sheffield Scientific School, New Haven, Connecticut". Lost New England.

•  Done Same as above.

Just as a general observation, could the selected projects which are only backed up by a potential unreliable citation (see above), and do not have a NRHP, NRHD or LHD status, be removed from the selected projects list? Comment: Of course. At this point, I have gone through and replaced all such sources.

• From conducting source spot-checks, I am content there has been no OR.

• A few instances of possible close paraphrasing have been addressed. From source spot-checks, I am content there has been no copyvio.
• Copyvio detector brings up nothing of concern.

• The article contains information of Cady's businesses and career, his associates, personal life, and his involvement with architectural projects.

• Article stays focussed on topic. There is a lot of architectural detail, but focussed on Cady's involvement.

• The content of the article is presented neutrally.

• No evidence of instability or edit warring. A lot of recent edits are by nominator.

• All images are tagged with copyright status.

• Images are relevant (either of the subject or of buildings discussed) and have captions.