Well, I may end up pulling translations for other data, although I don't know how much of the work I'll be arranging to be done will crossover with the work you're doing.
Granted, I'm using the game as a source directly, as opposed to a wiki, so...
At my end, I'll be arranging for translation for:
Songs, costumes, accessories, stages.
I will also be arranging for the flavour text from all of them. Namely what the game will say when you highlight the item in question (so partial song lyrics for the songs, a description for costumes/accessories/stages)
I don't know how useful any of this is, because well a lot of the stuff I'll need to do isn't gameplay based.
I'll also be arranging lots of screenshots of both the grids, and the preview for every idol. You may want to use some of those, I don't know.
I also note that you're missing a stage in the stage list (Unless I'm also counting your list wrong)
There are 40 stages, not 39.
This might be a case where we might want to meet online so I can stream everything, so we can determine what you need screenshot wise and I can provide that to you.