Well the area of Baltic lands seems pretty raped in your campaign map. So I found this map for 8th - 11th centuries.
Map is in Latvian language but I am sure you will understand the settlement names and tribe names.
[img=https://img105.imageshack.us/img105/4844/vikinglaiks9nt.jpg]

You can see major trading settlement names that time in Baltic. They are represented with black dot in the middle.
I will give some basic translation for some region names into English (though i don't know if you will stick with names in orginal languages in your mod)
Druza - Prussia
Jurpils - Curonia
Daugmale - Semigalia

I don't know which provinces you will include in mod, but your Baltic land area in campaign map doesn't make any sense to me.
If you have any questions about Baltics, just ask me.