I would rather say that the files on the "sound" folder are actually SFX, and that the ones on sound\Synth are the actual music from the game.
I was able to convert the AAX files there with VGMStream with no problems at all, using the utf_tab suite to decrypt the big CPK file (the CSB files can be decrypted with csb_extract.exe, but I don't know what to do with the resulting files).