Bombard bizarre shooting error

I'm here just sitting at my monitor staring at 2 the Empire bombards guarding the first Siege Door across the first bridge over the chasm in the first level featuring Mira (you might wanna consider to add the level's title somewhere for quick reference while playing in the future). I have no minions other than 10 workers trying to claim the land across that bridge. The left bombard constantly shoots off at a location almost coinciding the the one to the right, sometimes tho even managing to hit the door beside it, despite clearly aiming somewhere else at the workers, at a rate of 3 accurate shoots per one wild on average, varying by a moderate degree. I have no explanation why the other bombard almost at the same place doesn't exhibit this phenomenon.

Save game — have fun!