I earlier rewrote the introductory paragraph for commentary, possibly due to a misunderstanding as to what this tag is actually for.
The first wiki said this:
Posts with this tag have the artist's accompanying commentary from the original site translated and posted as a comment.
Pretty unambiguously for translated commentary. A few years later it was updated to say:
Posts with this tag have the artist's accompanying commentary from the original site posted (and, if necessary, translated into English) as a comment. For untranslated artist commentary, use commentary_request.
Now it seems to say the tag is for any presence of artist commentary, regardless of whether it was translated by a user or not. It may also be implying that the commentary may or may not allready be in English. However, it also states to use commentary request for posts containing untranslated commentary, implying commentary to be analogous to translated. The part about posting the commentary as a comment was also removed a few years later, since a separate field for artist commentary was added. Then a few months ago it received its last major update, saying:
Posts with this tag have artist commentary which is completely rendered in English or symbols, with any original other-language commentary, if present, kept in the "original" section of the commentary field. For untranslated artist commentary, use commentary request instead, plus the corresponding [language]_commentary tag if not Japanese.
This one is now clearer in the fact it only applies to English commentary, whether translated or not, but it's written in kind of an asinine way. Definitely could've been worded better. Still has the problem of implying itself to be a translated equivalent for artist commentary.
English commentary was implicated to commentary in topic #15162, but undone soon after due to issues with artist commentary containing multiple languages.
This is where my confusion lies. Why are we tagging english commentary posts with commentary? We already have a tag for commentary written in English by the artist, it's called english commentary. If the original intent was for commentary that was translated by us from a non-English language, how exactly does commentary that was never translated by one of our users, because it was already written in English by the artist, also fall under that umbrella? That doesn't make sense. We don't tag images featuring English text as translated, we use english text and move on. No one would use commentary to find commentary that's originally in English, because it's filled to the brim with non-English commentary that has been translated. Likewise, commentary now has 45k posts that never needed to be translated to begin with, which if you wanted to find you would just use english commentary.
I can't think of a single benefit to overlapping these two tags like this. Effectively, commentary is being used for two completely opposite things: commentary that has been translated, and commentary that hasn't been translated, only because they end up sharing the same language. At that point, commentary might as well just be aliased to english commentary, since being in English is the only thing they have in common, despite the fact one started in English and the other didn't.