[TravelLog]

You might want to consider some of the fey races (which you mentioned in your Cosmology section), as malevolent mischief makers that gain power from mortal suffering and negative emotions. It could certainly give the world an interesting feel if nothing else.

Some other options are Duergar, Mongrelfolk, Skulks, Yuan-ti, Kua-toa, Troglodytes, or even Kenku.

Edit: I think it might also be beneficial to add some other playable races that act as minorities among the four nations, as otherwise the number of available races is fairly limited, and would result in some pigeonholing in terms of race-class dynamics.