Hmm, I hadn't thought about that! I wonder if they'd be willing — a lot of their website is under a somewhat vague quasi-open-source license, but they might be chary of "helpful" outsiders who want to "help", as I'm inferring they've had some bad experiences in the past.

They've translated some of their pages themselves, although the translation is somewhat out of date: http://www.biyubi.com/eng_principal.html