Well in regards to the OP, the lead teams are all Japanese. Obvious fact is obvious, but it's quite possible that just like a lot of people where I currently live(Puerto Rico), they may be able to speak English and read it, but are nervous about writing in it since there are a lot of subtleties that need to be taken into account when writing stuff. Hell, I speak near perfect Spanish, but I don't like writing in it for that very reason(maybe I'm just projecting >.> ), so I can't really judge anyone for it.

I'm sure though that if it's something that really needs to be transmitted to all the forums, they'll get right on it. Otherwise, much like the OP, take the time to learn Japanese. Aside from letting you read the forums at your leisure, it's always handy to be multi-lingual when heading to a job interview.