ActivityPub has a feature where most post objects can actually have different language representations within one item. On a protocol level, MissKey/Mastodon/Lemmy can have the same message in different languages, and the client can pick the one to display. Unfortunately, I’ve never seen anyone make use of it. Seems like a waste. If used, users with their display language set to German/Japanese will see the “machine translated:” post first, and people with English as a language will see the original. English first, and good implementations would allow the user to switch languages to compare.