When a gaul usses traps. there is no incentive to force the attacker to return for the troops or disband them other than the wheat cost.. wouldnt it be better if 5 or 10% of trapped troops died every 24 hours and half the traps was repaired from this feature.
this would free up wheat at the attackers. free up traps at the defenders.. and maybe also encourage either to disband release them or the attacker to try to release them..
would make attacking gauls more hard at the start, but mean gauls get repeated attacks more likely later on in the game.