I must admit, I never found a way to fix bank 01. It seems like there was something odd going on, I think they're all valid sounds but I never could figure out what made some work and others not.
On Bank 0A, instrument 04 isn't present. It's not a bug, just a null pointers in-game instead of an instrument (00000000) offset.
The reason some instruments repeat many times is that it actually is in there that many times, but different volumes. I don't think I show volume though, so it's not that useful.
That is odd bank 18 has that chant too, but I guess it does. It points to the same offset: 0036C840 as with the other chants, so barring changing some of parameters by sound to make it sound radically different (like pitch, volume, etc), guess it bizarrely is the same. Maybe it's used, maybe not. Even more interesting is that version 1.2 still has this chant in bank 18
But not in 0A.