I'm sure this has already been mentioned, but since
@Thunderbrd has mentioned a unit review in the past:
The Neanderthal Clubman has a -75% city attack modifier for some reason? Even though regular clubmen don't. That problem goes away when you upgrade to a Neanderthal Spiked Clubman, but they still don't have the Clubman's normal bonus vs melee. I've also noticed that the Restful Recovery Buildup seems to not go past the first rank even though there aren't any tech prereqs that I can find. It's possible that's also a bug relating to the Neanderthal Clubman, I haven't checked with other units.