It's not as complicated as some perceive. When ECAM warning comes first person noticing announces it and cancels it. PF has to notice it because control law may have changed, take his time to fly may be he needs to level off, or hold at PP so inform ATC accordingly and once he is satisfied order ECAM action. PM can read actions under particular title PF acknowledges but before clearing that title he needs to glance and see actions done or grasp the meaning. Even in Alternate Law only bank is not held with FBW but flight path is stabilized periodic scan of basic parameters is sufficient and not so difficult. The duties are split but there's no wall.