I'd lower their armor's tech level to industrial (as i assume they're spacer right now) for balance reasons

Centipedes are incredibly resistant to even charge weapons,which bounce off 50% of the time,there's no weapon in vanilla that can deal with them effectively (you have to use modded weapons which have 80+ penetration)

My colony easily mows down any human raids or manhunters,but centipedes? That's a whole other story,right now I have to use the anti tank rifles from vanilla expanded,which can kill a centipede with enough spam,and for extreme late game there's vanilla expanded laser