(reposted below with the link fixed)
Unfortunatly, your link is broken.
The link I pointed was just an idea because I have no idea how it will look on your map. You might need to adapt if you want to take that style.
Regarding borders, in particular internal borders, another common delineation is roadways. I notice you don't have any settlements identified yet... some of those borders could be major roadways connecting settlements, while others, where topography allows, could be rivers that aren't big enough to be recorded on the map.
Ok, I tried painting the borders a little thinner, and then an idea hit me.
I created a duplicate layer of the borders, blurred it, then used the original to delete the middle of the blurred lines. The borders are still there, but they're subtler and less obtrusive.
I played around with coloring the sides of the borders, like in the examples you showed, but the coloring of the topography interfered too much. How's this?
The roadway idea is an excellent one. Kiridin is a land of barbaric nomads, and much of their territory is likely marked out by trails.
The anchors are meant to represent settlements in the Shadow Colonies, by the way. The colonies are an offshoot of a seafaring nation, hence the choice of icon. Each anchor is meant to represent a colony's capitol town.
I think it look good but maybe you should increase the opacity of the labels a little.
Ok, another update:
+Per Azelor's recommendation, I increased the opacity on the labels, though I kept at least a little transparency for most of them.
+The ocean is darker and has a bit of texture now.
+I toned down the blue of the rivers (was too bright earlier)
+Per Azelor's earlier recommendation, I re-worked the compass rose to be more lighting-consistent.
I added in a small canal to the island in the north (correcting an earlier oversight)
Pending any other issues I've missed, I think I'm just about done!
Yes, I think it's good now. I don't see what you could improve.
Thanks for all the help, Azelor and Gumboot! I've posted it to the finished maps section.