another thing I forgot to tell (i hope this is the last ) is that I already checked the files with windiff, and included on the new list only the different ones, except the acf dir, the voice files and things like save icons. I used Dimkaua's post on page 5 as a reference.
I tested just now, extract the files from the U.S. version and JP version and replace the U.S. files in the JP folder according to rootR_newfiles and change the folder name jp_files to us_files and used the cpkforp to make the rest, so whats works.. title texture 100% menu texture 100% dialogues 100% names of the characters 100% map, dungeos, cityes names 100%, and the rest of texts in menu are works fine but still in japanese.
the only error I saw was on the menu of the monsters. perhaps an error related to these files book_users.bin book_enemy.bin book_discovery.bin book_collect.bin remembering that I just modified the rootR.cpk, the map0R.cpk and map1R.cpk have not changed or replaced by US version
I have tested with the japanese ones, at least it gave no errors in the game font, after I do some more tests, any progress I tell you.
I just finished a new tool which can replace all files in the rootR. I also attach a modified unpacker script that dumps all files still compressed and a modded tocdump (dumpextsize) that only makes a filelist, but this time it saves the uncompressed size of the files. You will only need this list.
To repack, place all the files (uncompressed or not, doesn't matter) to a directory. For best results, unpack both US and JP keeping compression then copy the files from the US dir over the JP dir. This means you can also use big files like voices. Running the repacker it will take some time since has to check 2111 files, but it will finish.
I can't test the results right now but the new file should work correctly with the unpack script.
Note that this only works with the (JP) rootR.cpk, with exactly 2111 files.
About the trophies, it could work, there are some differences in the data part, but most of the file is same in both versions. Or we can just replace the text in it, it looks like they are in same order.
there are minor visual gliches, like the numbers are too close to each other in the menu, there is a black bar when you enter a new place (missing texture?), and some letters may not show if the skit line is too long, but nothing serious with the gameplay.
i don't remember problems with monster names, but I will check it.