So, I'm going to start off by saying... I am still subscribed to this mod and you should be too!
I was using the "normal" CW2.0 weapon base, and then I switched over to this "updated/fixed" version. My bullet penetration now works (aka. it will do damage through walls) I am not trying to advertise for my benefit, this is just a quality of life adjustment that I was searching for and I thought I'd share it.

NOTE: If Othereum wants me to get rid of this discussion on his addon page I will.
EDIT: It only works on some materials, I'm not entirely sure what specific ones though.