The weather areas listed in the game are more of a nod to player convenience than anything else. I think that just about anyone can see the term "Mediterranean" and know what it means. "Sem-arid, sub-tropical", while scientifically accurate (I guess, I'm taking your word for it because I have no idea) is not all that descriptive to the layman. Just like we assume that everyone in the BattleMaster world speaks the same language. It's a bit of handwaving for player convenience.
As to the world maps, no official world map exists, and I believe Tom has stated that he has no intentions of ever making one. The exact relationship of the continents to each other is indeterminate, and will stay that way.