not a problem at all to extend. The tutorial also says how to fix them not playing right. It's about the sample. It looks like this: 30 3c 00 00 XX XX XX XX FF 00 FF 00
The XX is the pointer.
Change it to 00 3c 00 00 XX XX XX XX FF 00 FF 00
it will now play correctly.
I am with romhackers online too I think, I'll sign up with that too.
Also facepalm for not thinking of this but walking into a wall! That thud sound! That takes a DS track doesn't it...? SO we really only have 11 tracks to use in theory minus maybe script songs or battles... but they would use a couple tracks too I guess.
Have you tested that out much? Cause in your vids you never walked into walls