In theory, yes -- but tbh in practice, I tried using the multilingual version of whisper-tiny and saw significantly worse performance, so that's why it's english-only at the moment. Possible that there's some sort of parameter/tuning that could improve performance though, I'm looking in to it!

> Would it be easy to add other languages than English?

I think so, yes. The website uses whisper-tiny.en, so I suppose all they need to do is switch to whisper-tiny instead.