If Howling Moon should be updated at any point and I receive some answer here:
Razmen/HowlingMoon#4

Howling moon has been updated for 1.12
https://minecraft.curseforge.com/projects/howling-moon

I have a few of my server players testing it out in single player alongside Vampirism to check for any conflicts or weirdness

A good integration here might be for the vampire hunters to also hunt/attack werewolves. And vice-versa, for the "werewolf hunters" to also attack vampires.