I downloaded the mod after the video from GNS, and what I can say from my experience is that
1/ in my established game, I was drowning in wolves, wolves spawned repeatedly, throwing themself into my tunnels and choke points, a literal mound of wolves. No zombies.
2/ in a new game I started, I came across no wandering hordes until I dropped my land claim block, at which point they started and never stopped coming. Can't use my base at all because it is perpetually under zombie siege, which look, zombie apocalypse and all, but even leaving my base and going to do some pois, I come across no hordes, but the second I return to my base, there's easily 20-30 zombies waiting for me, clear them out, another group spawns immediately.
Gonna have to delete the mod which is unfortunate because I like the idea of it.