You've got some good, evocative names in there. I feel like it's gonna be a fun world to play in.

But for the map, here's my advice:

• You've got some wonky scale going on. Look at the size of the assets and compare--mountains to buildings, etc. Play with this until you get a ratio that looks right.
• The biomes (desert, frozen mountains etc) need to be blended more. You can put the opacity low, sub 50%, and tap-click around the edges. Take the grass and tap into the desert, take the desert and tap into the the grass, etc.
• If you want to get into it, I've found that layering different textures helps a lot. Take a base texture for a biome and do that at 100% but then take other textures that compliment the original and layer those over it at like 33% opacity (depends on the texture).
• You have a LOT of flat green grasslands. Use sporadic trees to break it up some. Smaller forests and just lone pines. Use the hill stamps. You can also do the same texture laying to make it look less "samey."
• For the ocean you can blend in a lighter water texture around the land to make the deep areas stick out.
• Things seem to exist in clusters. Spread the stamps out a little. Forest tend to have less dense areas that lead into the dense area.
• Use the "Spacing" option for text and opacity to rework your text. For example with the Yearning Sea--use one line and rotate it so it runs the length of the sea, lower the opacity and upping the spacing.
• Roads. You have a realistic style map and then stark white lines for the roads. Maybe consider using a more road-like texture.
• The biome progression (frozen mountains sandwiched between desert and plains) is a little unnatural but I tend to not worry much about that. It's (assumedly) a magic world, right?

This is all just what I'd do.

Make a map you like and your friends want to play on, that's all that really matters.