Your mobs are over spawning in the warped forest region of the nether stopping ender men spawning i have been to many different warped forest biomes and have not found one enderman.

+1 on this, it was a journey to find ghasts ... i think the main problem relies on the hell cow, but i'm not sure.

I can lower hell cow spawn rate in next version and can see if that fixes it

I can lower hell cow spawn rate in next version and can see if that fixes it

I did some debugging and noticed that the Hell Cow is registered as a MONSTER, making it a hostile mob and sharing the mob cap with ghasts, piglins, etc. I'm not sure if registering it as hostile is intended, but I think changing it to CREATURE can improve the results here.

I can test this it later ^~^