Part One:

(Required language in ask)

So basically the title explains itself, before a user can post a question, they must specify their language(s). If the user has a question mostly relevant to repl, they can also choose repl.

Oh also, It would be nice to have it as a drop-down for the next step (including a customizable other, of course). Or like stackoverflows tags.

See for part 2 of this idea.