I do not hear any new ambiance sound fx coming from the newly added biomes. Im running a modpack with dynamic surroundings and charmonioum. Other BetterEnd Biomes seem to be fine though.

Weird. So are you experiencing this only in AmberLand and SulphurSprings biomes?

Solved the issue, in the next version custom music will actually be played in the new biomes, also notice that not all the biomes have custom ambience. I will close this for now