Hey! I'm the dev who made this:) I think that you are right, data will bias towards english because we have a dataset that people can use that is in english. But you can also upload non-english docs into the battle mode as well as the playground!
LMArena splits their leaderboard by language: maybe you should consider doing the same thing
I assume to do that you’d need another model to do language detection on the inputs and/or outputs; but a language detection model can be a lot cheaper than an OCR model or an LLM
