I've been grinding at this for a while now, and have gotten some inside information too about it. I've used the .dpc extracting .bms script that already exists for ratatouille on the files and its only outputting .DAT files " http://aluigi.org/bms/asobo_ratatouille.bms
Apparently according to backups of the game that the devs have, the sounds are stored as .VAG files. I've been simply just switching the extensions around with no avail.
These should be the sound files, as they have descriptions that match up with game context. EG. DTH_DROW, DTH_EVE, DTH_FALL, matching up with death cutscene context.
and bunch of START and END named files.
I have a friend who works as a DJ just having a look at the files, but he does not know much about converting unknown files. I wish to have the library of sounds from the game for use is some small personal projects
some of the sounds from the PS2 wall-e game are pretty much exactly like the original files for sounds from the film!