This mod doesn't add any zombies, just spawns in zombies (from the entityclasses.xml & entitygroups.xml configs), so it should work with it fine.
No I am not running any biome mods, I removed the no screamer zombies mod and added the reduced screamer mod.
Now I am getting zombie hordes with screamer but I didn't check to see if it was part of the scheduled horde or it spawned because I was using too many forges and cement mixers.
Will take a look next time it happens.