While waiting for the last bits and bobs, I tried to get the music fading in and out on zone boundaries. It worked, but it caused problems when warping, with music tracks stacking. Then sound started being weird, with almost all effects popping and crackling. The more I tried to fix it, the more everything broke worse and worse. In a panic, I deleted the project and restored from yesterday’s backup, thankful that I had one.
Moral of the story: backups!
Also: Construct2′s sound engine is really not that great. I’ve had to remove volume adjusting, since it would just make effects crackle or cut out. I kept in the mute button, so that’ll have to do.