Most Helpful Girl
You call it the deserving adjective.
Ex: a lousy restaurant that's largely ignored is lousy, not underrated. A phenomenal athlete who is as amazing as the heaps of praise he or she gets is phenomenal, not overrated.
Those terms exist to explain that there is a gap between perception and reality of an object/experience. "Fairly rated" is indeed a good way of putting it that I see here.2
Most Helpful Guy