This may be a bug, but the Japanese new unique technology also apply to bombard tower! This mean that their bombard tower fire 3 canon balls!
That's 3 Bombard tower for the price of one, and at the same place!
I'm no expert, but that does seem a bit OP, and probably the result of a bug.
Edit : I discovered that in a scenario where the Japanese Town had Bombard Tower (Kyoto in the battle for the conquerors). I had forgotten they can't have bombard tower, normally. But that means that if they have these in a scenario, then it fires 3 arrow.
That's 3 Bombard tower for the price of one, and at the same place!
I'm no expert, but that does seem a bit OP, and probably the result of a bug.
Edit : I discovered that in a scenario where the Japanese Town had Bombard Tower (Kyoto in the battle for the conquerors). I had forgotten they can't have bombard tower, normally. But that means that if they have these in a scenario, then it fires 3 arrow.