My CRV overheated due to low radiator fluid. In the past couple of months, I've needed two valve jobs. Could this be a result of the overheated engine?

Yes, it's the result of overheating. In aluminum head engines, it frequently results in valve damage, head warpage, head cracking, and head gasket failure. Make sure and only use a 50/50 mixture of antifreeze and distilled water. Tap water has minerals that eventually buildup in the radiator and block passages.