This mod make biters go through walls. Don't use this.

Sorry, you're talking rubbish.. Been using this for years (and all I did was port it to 1.1) and never seen that problem. There are certain types of spitters that can spit other biters, and these can, under certain circumstances go over the wall, but that's by design.

Can you please provide details, what other mods you're using, and potentially a screenshot.

I does, but from what i've found, this is only in combination with Combat Mechanics Overhaul, i believe? something about Collision Layers.

1. There are Unit-Launcher-Enemies, they will spit a bunch of small units above any wall.
2. There are Wall-Breaking-Enemies, they will do whats their name .

But:
What is the difference between NE an NEBuildings2? Related links depends only at NE

I like the mod, but with it installed my biters can scale cliffs like nothing and walk on water like jesus. I do have Combat Mechanics Overhaul, so that probably has something to do with it.