tip: hetalia f/f sort:kudos
Probably only future works. Afaik AO3 has no way of detecting which works have the wrong language marked, and even if they did, they couldn't change a work's tags without author's permission
Language is one of the few tags they will change, actually, as the last paragraph says. The other tags are Archive Warnings (will change to Chose Not To Warn if reported as needing one of the four big warnings), Rating (will change to Not Rated if necessary), and, I believe, Fandom. But you are right that mislabeled works are not automatically detected. Just reported works.
Ah, I didn't read that last paragraph well enough before commenting. Thanks for pointing that out
Interesting. Thanks for spelling it all out! <3