An old project that never advanced because I was missing a tool; now I have it and I am here to ask if somebody is interested on a translation.
I don't know if i really can complete this project alone because of the ASM hacking required to convert the glossary system but I thing the museum is what matters most.

Emm...maybe you should inform yourself before voting :p
And what means "newest DS Ace Attorney game"?
A game that already is released in japan (last february) but not will be localized in the usa?? No, that is Gyakuten kenji2.
The game that is still not been released but announced to be localized in the usa?? No, that is Prof.Layton vs Phoenix Wright.
The games that are speculated to be announced next week at the TGS (Tokyo Game show)?? No, that would be Phoenix Write 5 or Ace Attorney Investigation 3.

Gyakuten Saiban Jiten (rom number 0996) is an "anthology" (similar to the 4° disc in FF7 International or the "Omake" mode in Chrono Trigger PSX/NDS) of the original games from the GBA and the added case of the NDS remake.
See all the intros of the cases, all animation of the characters, all backgrounds, all places, all evidence etc... of the first 3 games Phoenix Write.

Yes, you  can listen to all ( i think) song but saddly you can't choose a song and to look the evidence (for example)... you need to stay on the "music" menu and they are divided by game and case.

You normally not find it because it's not really a game and released back on 2007.
Even the ace attorney wiki don't lost it :http://aceattorney.wikia.com/wiki/Ace_Attorney_Wiki
You can find the cover and some screens at gamefaqs: http://www.gamefaqs.com/ds/944888-gyakuten-saiban-jiten/images

About the language option, there are almost 8000 files without any header to find out if they are a NCLR (palette), NCGR(tiles) or NSCR (tile map). Believe me if i say that if I do this, I do it only 1 time.
The good news is that after I have done it and created a map of all files, the next guy have more a easy life doing a retranslation and actually some french people are interested on it but not expect their work before 2 - 3 years.

As for AAI2, that is not a game that somebody will translate alone, anyway I have a good news for you again: there are a English, french, german, italian and probably a brasilian translation on the way but again, don't expect any of this translation completed before 1-3 years.
If you are lucky...maybe a case1 patch for Christmas.

We only got the main 3 Phoenix wright titles and Apolo Justice translated in French.
Even the others games which are officially translated in english are unplayable with my current english skills, so much they use complex language. (or I'd need to check up a dictionary on literally every sentence in the game which wouldn't be very fun).

Génial !!