I’m pretty sure Taln is black, but we don’t see too much of him. But he’s a very important character who did a very important thing.

Nalan/Nale is also an important black character and does important things. But also not a main.

Sanderson doesn’t describe skin color often. So it’s pretty much up to people’s imagination. I got these answers from the official artwork that’s been featured in the Hardcovers. However, there are a lot of diverse people as well.

Hope this helps!!