collision has been an issue since forever, but the biggest offender isn't even infantry, that one is maneageable to some degree, the worst is actually cavalry charging through units as if there was nothing there, be them friendly or foe... They only stop if the ridiculous prancing effect comes into play by someone stabbing the horse, which's also quite ridiculous considering the rider gets stun-locked until the animation finishes (feels extremely uncanny)
So far I feel TW doesn't give a F about it because it should've been patched to be properly tested, if in 2 years it wasn't done, I think they want to shoehorn this crap at all costs.