SFX ripping/decoding/dumping features?

[Shonumi]

Knowing that Factor 5 absolutely loved to do unconventional hardware tricks (the ucodes for their N64 games for example), I'm inclined to say it's a custom format then, more likely than not, especially since it was among the earliest of GC games. They never seemed to do anything in a straightforward manner :p

EDIT: This game does have a Sound Test mode. The password in COMPOSER. You could manually dump things and edit the files in something like Audacity (Dolphin can dump the audio output to a file, it's just the final mixed results of all the current sounds playing, but Sound Test should only have one sound playing at a time). That might be the best course of action rather than spending hours reverse-engineering one of the most obscurely coded games for the GC.