I'll echo what everyone else has said - awesome job!!!
As far as official sources for the rest of Davania are concerned, the answer to that would be "not much". AFAIK the only hex maps covering even a slice of Davania ever made were:
1. The map of the Sea of Dread in the PWA (AC 1011), scaled at 72 miles per hex, which I used as a starting point for my own continental map of Davania, as well as the basis for 24-mile hex map which you just beautified. I don't know if Thorf made a copy of that one, but if you look at my map of the Adakkian Sound region
, you'll see it, as the whole northern coast was copied from that map. Failing that, we'll need to scan it.
2. The map of the Serpent Peninsula (copy by Thorf
) from CoM, which was scaled at 24 miles per hex. This one has the immediate region around Kastelios and Garganin.
If we were to combine the info from map #2 with the map John has just done, you'll find that were only looking at about 4 72 mile hexes' worth of space to render as 24-mile hexes. If we do that, we could bridge the intervening territory and have a 24-mile hex map of the northernmost coast of Davania from Kastelios to Raven Scarp.