Two things I noticed - and it would be great if you could do something about it, although it might sound like a luxury complaint:
1. You can choose a different background music etc. for different zones within a level but not a different step sound. Imagine creating a dungeon with e.g. a small flooded area in it: The sound of stepping on stone wouldn't feel right if your characters actually wate through water, Designers trying to work with authentic, atmospheric sounds would therefor have to create two dungeon levels (one for stone floor, one for flooded hallways) only because they need another step sound. It would make more sense if you could define the step sound according to zones WITHIN a level, not just level. I realize most designers might not care about step sounds that much so it's not top priority, but if it's easy to implement that option, I for one would really appreciate it. :)
2. You can choose a different background music for different zones and it will start playing as soon as you enter the zone - but: If you are teleported automatically into a zone by a Transfer Module event (as opposed to stepping into it), the background music will already start playing, too, but recommence playing once you do the first actual step inside the zone. That kind of ruins the background music effect. There's a workaround for designers if they don't mind that the music will only start with the first actual step. But IMO it would be much more elegant and useful if DC would realize you are already IN the zone when teleported into it (and apparantly it does, in a way) and therefor NOT treat the first actual step as if you were only just entering it.
You can scrub #1, as I learned there are already satisfactory solutions for that included in DC.
But I've identified two more issues similar to #2:
One is the Camp Music - if you choose certain options in the camp menu, then exit the submenus and return to the main camp menu, the camp music is aborted and starts from the beginning.
The other is the Transfer Module event - as soon as the party is teleported, the level music starts from the beginning, which is fine if the party was transferred to a different level but treacherous and annoying if they remain on the same one and are only teleported to a different spot (like with UA's Teleport or Stairs events).