So I broke the Veldt...

Hmm.. that was a great thought, but it didn't seem to do the trick. Is there something within the Barren Falls event that resets the music? I re-wrote probably 20% of that event, so I may have inadvertently changed something.

This event bit:
1BB B7:3 Veldt music plays on the overworld map

 Yep, I think that's it. I rewrote the Barren Falls boss battle to happen on the Lete River, so I load from the Lete River map to that event, and I purposely skip the first few bytes so that I don't have Terra take a step backwards before jumping. Didn't realize I was skipping the event bit in the process! I'll test it this evening.

EDIT: Yep, that did it! Thanks Gi. I thought for sure the data was embedded in map data, not in an event bit.