Let's call this what it really is- a bug. Archers shooting thru walls is a bug. There's nothing you can say that changes that. Even the mmorts World of Battles has it where archers don't shoot thru walls, and use Line of Sight.
As a customer who is/was waiting for this game to release on Steam, I will not be buying a game with this bug. I will post this bug on the Steam forums so that others will know about it.
If you fix the bug, you don't have the other issues messing with the siege. I don't mean to be rude, but a bug as big as this, can not be ignored, or assumed to be a "game feature".
Thank you for reading.