I like the Raevan drawings. When thinking through their physique for Shani, I did some wing span research and, without magical intervention, physics alone put them with a pretty impressive wingspan. Going by flighted birds with at the approximate weight of a smallish humanoid (~100-125 pound range) and adding the wing weight, they'd need roughly 20-25' of wing span to get enough surface area for flight. I'd originally kind of seen them as having wings similar to the drawings but, after the research, realized they'd need another joint, so instead of coming upwards from the back and then down, the first segment of wing would go down, then up, and then out.
That same line flowed, for me at least, into the layout of Sachia itself. Any kind of structure would probably have larger halls and doorways than needed by a non-winged humanoid, and great rooms would likely be either open air or have significantly higher ceilings to allow for limited flight. Much as movements and gestures are expressive for humans, so would flight be for Raevan. Development on the isles themselves would also probably be less than friendly to non-flighted creatures - i.e. why build bridges, ramps, or stairs? Extending this, I imagine the Scael would have similar aquatic features that simply weren't designed with non-aquatic creatures in mind.
Oh, and update - Warm Regret and I have been working via PM to get things sorted out. Once I've seen the new character, I'll update my CS to sync appropriately.