If you don’t choose the same language as the top-level comment you cannot answer in the same tree. The wheel will just keep spinning but when you look at the API request you see that it returns something like “bad language” and upon choosing the right language you can comment again!
This is super helpful, thank you for explaining! I’ve run into this problem several times now where it didn’t really make sense (I dont think there was a language mismatch) but at least I know what was going on now!