Oh, man, this is so going to rock! "Facing" and "Final Confrontation" for Magus v. Dalton? Priceless. Excellent work on this, guys!
As far as such imports go from other SNES games, you're only considering Square games, right? I imagine implementing music from, say, ActRaiser II or the Brandish series would be murder considering the instrumentation would have to be imported as well as sequencing data. I imagine music from other Square games is much more compatible with the way Chrono Trigger does things.
Ooh, man, I just remembered "Northern Hemispheres" from Donkey Kong Country. T'would be interesting for Mt. Woe. Another snowy theme applicable to Mt. Woe would be Tactics Ogre's "Ice Battle Theme." And, ah! "Sonia's Fortress" from Equinox. But once again, technical aspects make such things a pipe dream no doubt.
Bahamut Lagoon had some interesting music, and it was a Square game. One piece even sounds as if it could pass for a variation on Schala's theme.
Too bad Square didn't do Tales of Phantasia. Oh, hoh hoh, that beautiful music!