I think it just defaults to Plymouth if you don't set it.
It was sort of intended that the AI is put in the middle. That's where it is in the multiplayer games. It was meant to seperate the players. Sure it's a little odd for a colony game, but like I said, it's a straight hex edited conversion.
I mainly did it because we seem to have quite a lack of AI levels, particularly for colony games. I figured it'd be an easy way to add another 2, even if they weren't exactly everything everyone always wanted.