The funfedi.dev support tables contain an example. Unfortunately, codeberg has hiccups and the site is thus unavailable.
From what I recall: No application tested by funfedi.dev supports the feature properly.
I'm also skeptical that proper support is possible. Just consider the text is available in German, English, and French and an image alt text is available in English and French. The person decides to display the post in German. How do you decide the language of the alt text?
The above is an example. Being able to resolve that question does not really resolve the question of how to go from multilingual object -> single language object to display, with all possible cases considered.

For example: an indicator could be shown that other languages are available for a post, and allow switching to a different one (compare with the Edited feature), and users could choose the languages to show by priority, if missing, etc