i don't know if i understand all that you say, but i put an update of the map.
Now the Tower can bombard only the 5 territories adjacent the fosses and in the same quadrant (example: Tower4 can bombard Mountain 1-5-6 and Court 7-8 but can conquer only the Courts) and the catapults can bombard only the tower in the same quadrant (example: Mountain 6 can bombard only Tower 4).
How you explaned (sorry but i didn't know it..), with the bombardaments you cannot conquer the territory but if its army go to 0 it becomes 1 neutral army.
I also put 4 bridges in the map. From the bridge, the insider territory can attack the outsider, and vice versa, and the fosse can attack insider and outsider and vice versa. (example: Court 1 can attack desert 6 and vice-versa, and Fosse 8 can attack Desert 6 and Court 1 and vice-versa)
The other Fosses can be assaulted only from the Courts (and the adjacent fosses), but can attack adjacent insider and outsider territories. For this reason i raised the Fosses' bonus to 7, but not to 8 (thanx to its particular advantage versus the outsider territories).
It's ok or i did some mistakes? ^_^