A tank on a berm can't target tanks behind a berm.
Unless it's the same berm, right?
I was also wondering if a tank at an end of a berm can shoot along the berm at a tank right at the base of the opposite end of the berm. Sounds like you meant for that to be possible, but I wonder whether a small LOS rule addition would not make the game more realistic in this scenario. The rule would be: if you shoot across the berm, then you cannot hit as many spaces beyond the berm as there are berm spaces you are shooting over.
2. Tank on a berm can shoot over destroyed tanks
Now that I think of it, I also see a problem with this, because destroyed tanks were shown to break LOS. I thought one of the principles was that the places you can shoot at, you can also be shot at from (with the possible exception of the extra space you get from shooting straight forward from a berm). Both tanks should be able to shoot over the tank in between or neither should.