I have found something.http://images.rpgnuke.ru/divinity_original_sin/concept/worldmap.png
Could this be the official map of the OS1 area?
Much stuff fits just well here and when I try to decipher it, the letters are readable.
Edit: Okay it seems to be that this map is part of the OS collectors edition! That makes it official and the map can be integrated into the worldmap it seems!
I was now able to decrypt the letters.
These are the words:
LATIN - English
URBS CYSEAL - City of Cyseal
ORA PRAEDATORIS - Hunter's Edge
LAPIS SACER - Sacred Stone
PALUS UMBRARUM - Dark Swamp
VALLES ARGENTATA - Silverglen
SILVA LUCULLA - Luculla Forest
PLANITIAE MAGNAE - Great Plain
SILVA LARUM - Seagull Forest?