@Gargron Okay. This is what I was missing, thanks.

By the way. This user is running their own instance. Every post of theirs gives me a translation offer on Mastodon dot social, but the language is the empty string. Is it possible some servers are sending a nonsensical post language?. https://mastodon.social/web/@suricrasia@lethargic.talkative.fish
I see Mastodon can't do much if the language isn't set properly, but the client software should be able to recognize the empty string is not a valid language input.