Right we could hide this composer menu if there’s only a single language… I don’t think we really considered “post in Y and we’ll translate to X, but we won’t translate everything else back to Y”… I believe we always had at least 2 supported languages in mind.
The locale detector agent will detect any language and set it, regardless of what the site supports in settings. Language support and detection quality will vary by LLM.
Posting as “not set” in a language unsupported by Discourse and setting an English translation by hand won’t work without AI at the moment. Manual translation requires a supported locale so the original post can be set.
Allowing admins to set additional languages for use in the composer menu might be a reasonable option to have for this case.