Banshaku recently
expressed interest in translating the wiki into Japanese. The first step toward this is installing
wiki family infrastructure to make "ja.wiki.nesdev.com".
I can't help with the Japanese translation, but I have many friends who do professional level Japanese translation (including one who works for Nikon doing technical document translation). I think most of the folks I know would need to be paid for their time though.
I thought it could be an idea but from Naruko's last message, he said that since there is no Japanese contributors and most Japanese has enough knowledge to read english, the current wiki is not an issue. Maybe I jumped the guns too fast. I'm aware of this situation in Japan. For example, many SDK documentations like iOS or Android are in english only so they have no choice but to read the english version usually.
If we do have a surge of Japanese contributors then yes, it would make sense. If not, translating by non native (like me) that are not fluent yet would make more a mess than anything else. It doesn't means that we cannot investigate how difficult it would be to install it but it's not a high priority.