Dont know if this has been reported , i am one of the people working on the AoE IV fandom wiki and i found that the (Royal) Cannon damage is not correct in the tooltip (tech tree etc) and possibly not correct at all. The normal cannon has 200 attack and the Royal cannon should have 20% more damage. So it’s damage should be 240, but as for now it is 220 in the tooltip/game.
Hey, thanks 
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We are aware of this one and working on a fix. Appreciate the report!