You silly hectopascals didn't get the one most used in canon: RTC. You know? Return to Castle. In all seriousness, though, I don't know if you should include that or not, since that's technically an official term, but maybe you should just for the sake of convenience? I mean, it is used by people, and those who only watched the Days movie might be a bit confuzzled by it (as they don't mention it there).
CTNW (Castle That Never Was) is also a thing.
Also, "Days Movie" might should also be listed in regards to the HD Cinematic of 358/2 Days, since a lot of people call it that. Maybe "Unofficial Days Movie"? I don't know... I also know some people who call Days just "358"... so maybe add that? And I don't know if you should mention a lot of people mistakenly call the game "365/2 Days" or not...
Oh! Another thing: If I remember correctly, TVA were called "Chasers" for a long time, before people knew their names. Yeah...
Anyway, this is an amazing thread, and I'm so glad I found this! Thanks a bunch for this, Sephiroth
It sure is a giant help, and it brings back many memories for me, as I mostly know all of these, too. Ahh the days of the BHK...
And actually, now that I think about it, I think there's a name that was used for BHK that's not listed here. If I think of it, I'll let you know
Also... does anyone think a thread like this should be done for TWEWY? I mean, KHI does cover it, and it's getting bigger (with terms like "Live-Chan" and "Hype-Chan"), so...