foobar2000 won't play certain .minigsfs

[Pingus!]

Instead of using "saptapper", I'd try GBA Mus Ripper. Google it, as I don't know if I'm allowed to link the site's location. If the GBA ROM uses the Sappy Sound Engine, it will dump the sounds into .mid's, which then you can feed the provided sound font (*.SF2) file that is dumped alongside with it to play the sounds how they're supposed to sound. It's more of a hassle, but it might be more efficient for your sake although.