After a while by the release of KH2 Translation Beta 1, I started to working on a complete unpacker/repacker of KH2.IMG, a file that contain all data files of the game.
After a lot of work I'm able to extract with the original name 30387 (!!!) of the 33728 files present in the game and repack them in a new image file. With this I'll able to add, remove, edit freely everything. I'm able also to decompress and compress the files (this will resolve the KH2 translation freeze problem) and PROBABLY I can add the english voices in Final Mix exclusive scenes (as the user Bajolzas advised me). Now I need few steps to complete the project:
1) Locate the name of 3341 files that I extracted
2) Obtain the english voices of 358/2 that KH2 misses
3) Finish to write the Shift-JIS table of KH2 to convert and translate the remain texts
I'm able to do these 3 steps but a day is too short and I've a real life (oh, this is my last year of High School and I'm studying a lot in these days), so if any japanese, expert of rom hacking or someone that tried to hack Kingdom Hearts 2 want to help me I'll appreciate :).