Ultrasound lets you replace the existing sound effects with potentially multiple new files, and either just pick one of the replacements at random, or cycle through them (and limit which replacement effects are used based on location).
Adding the new effects is the part that doesn't work yet.
It wouldn't be terribly difficult to add in support for Ultrasound to trigger sounds on events like 'battle ended'. Triggering on a certain piece of battle text would be possible as well, I guess. Might just take me a while to track down where to do it.