I'm on a server that has custom biomes on it, and I would love to define custom music for these biomes. However, this mod doesn't have an event for them! The ability to define events for biomes would be amazing.

Hello, the issue is not that this mod doesn't have an event for them, the issue is that your mod didn't make an event for them, otherwise it would have detected it properly. This is not as easy as it seems as currently I rely on a vanilla-like behavior with sound events, which needs to be registered on startup. I might do something that allows this in the future, but this needs quite a bit of time to think about to make it work. I will let you know if I succeed doing something for this