I literally only heard about this game yesterday and already everything else I have ever played seems inadequate by comparison to this masterpiece you are creating here.
There's only one thing, I think, that's missing that I, personally, have always been disappointed to find missing in big RPG games. A playable water-dwelling race that's as big and populate as those living on land.
Potentially you could have large towns and cities underwater with large markers above the water's surface so land-races could locate them for trade and such and areas where trapped bubbles of air allow air-breathing races to explore. You could also have the smaller towns (or possibly equally large yet less open-minded) without the air-bubbles and markers attempting to remain as isolated as possible.
These water-dwelling people could be advantaged in the obvious ability to breathe underwater and see clearer in water and could be disadvantaged with poorer sight out of the water and having their fatigue greatly affected by their hydration. They could also have smaller inventory space out of the water as they're used to their possessions weighing less. I'd imagine they'd not get on well with many races due to the drastic differences in their accustomed environments but would have a particular distrust for Avians (as would the Avians for them) based on how incredibly minimal interaction is between the species and would have a mutual hatred for Pantherians based on the Pantherian hatred of water but could be likely to get on with Reptilians as they share their ability to breathe underwater but would consider them foolish for forsaking the water to make homes upon the land.
The water creatures would be easily lost underground and on land but would innately be able to locate the nearest source of water and would be, by far, the best sea-navigators but would be unlikely to work on board a ship - partly because most captains would insist upon an avian navigator for their weather-sensing abilities, mostly because living so close to the water yet not being able to go in is a seemingly torturous experience to them - however they would be the most talented and successful sellers of seacharts.

I feel like I'm going on too much.... I'll stop now......