To my understanding ... The Bomber needs to be able to fly "accurately" to be able to BOMB a specific area of land where Soldiers may be fighting on the battle field. So the idea is that is you put into the sky a couple "Jet Fighters", they prevent the Bomber from getting the correct "accuracy" for timing the bombing of the troops...
Just like in REAL LIFE. Usually a Bomber is accompanied by Jet Fighters so that the Bomber can focus on its targets, this is offset by having additional Jet Fighters in the Air to do dogfights with other sky planes... Which may still hamper the accuracy of the Bomber (BTW).
So usually if enough cover is NOT provided, the Bomber will FAIL in its task of bombing the ground forces at the correct location.
Something along those lines, I think!
Note #1: In your world of math... I guess it means that the Accuracy of a Bomber = "2". Meaning you need a lot of precision to make a successful kill. ("12" or in my version "78" ... Because I think higher numbers should be 'more' favorable than lower ones...) But I'm pretty sure you understand what I mean with a "2" (High-precision).
If a bomber is blocked by a fighter.
If a bomber in a board game would be in range, it could still drop the bomb on the ground.
But in a card game, how do I justify that the bomber can't get into range if it isn't destroyed?
Maybe allow the bomber to drop the bomb anyway, if it survived the fighter?
In other words, a battle takes place before the attack. And the type of weapon determines if it is used or not.