I don't see why that would be the case. Your R4 archers would still be in the front. But your "front" would be 4 ranks away from your enemy's "front", not 2 ranks. So your enemy would have to charge for four rounds through your R4 archer fire to get to you. You could still put your cav on Rearguard, making them have to charge for three or so rounds to get to the enemy.
Ideally, add in a battlefield behavior control, to separate battlefield behavior from the currently overloaded encounter settings control. Then, if you have a heavy archer contingent, and not much infantry, you could do:
Archers: Middle/Hold, they don't ever move forward, no matter what
Infantry: Front/Hold, they wait for the enemy to come to them, allowing the archers as much time as possible to chew up the other side
Cav: Rear/LongWait, they sit in back for 4 or so rounds, then charge, and hopefully hit soon after the infantry lines meet
But if you have overwhelming infantry advantage, you do this:
Archers: Front/normal, shoot if you have a target, if not then move forward until you do have a target
Infantry: Front/charge, start as close to the enemy as possible, and advance into melee as quickly as possible
Cav: Back/ShortWait, give the infantry 2 rounds to move forward, then charge after them, hoping to hit at the same time, or maybe the round before?
Anyway... Just some random thoughts that have been floating around.