Add indicator to which language a status is set
I added a small indicator showing which language was set for a post, similar to Mastodon's web UI. Unfortunately, this often doesn't match the actual content of a post, but that's a different problem.

Since this feature is probably only relevant to a few people (or power users), I could add a setting to only show if the user enables it (default: not visible). Please let me know if such a setting would make sense.
Yes, this line hardly go on one line already, a settings near the translate button with a default to off would be nice thanks.
While thinking about this a little further, I came up with a slightly different (and in my opinion better) solution: the "translate" button now shows from which language the post will be translated.
Here's an example ("Translate from Japanese"):


That makes it clear, in what language a post was created (or at least which language is set for that post) and is even more descriptive than two small letters somewhere.
Very smart!