Small suggestion here: Replace Rhudaur Hillmen Warg Riders with Rhudaur Hillmen Horsemen. Canonically, Men and Uruks are too big to ride Wargs, that's why the smaller orcs/goblins only ride them. As such, the hireable unit should be replaced with Hillmen Horsemen. It makes sense regionally since horses are available in the Lone Lands, and for fairness to not take away a cavalry option to the hillmen players out there. It also gives a bit more diversity in the troop roster for angmar. Don't feel like wasting Warg riders? Boom. Cheap Cavalry.
In addition to this, Hillmen Cavalry should spawn in Hillmen invasions. Just wanted to point that out since I don't see Hillmen Warg Riders in invasions.