I could possibly think of a solution as a server suggestion for cannon to be working without interrupting other players since we only have one single world to share with the whole community.
possibilities are: Dwarf multi cannon to be only working as single combat in many area's. This means no random shots around so the solution is that cannons will only start attacking, and only the npc of which the player is in combat with at that time. Same mechanism applies to multi combat zones to not ruin other players gameplay experiences.
Black knights could be one of the few exceptions where cannon would work as its intended to be, could be an issue for other players doing diary so its best to instance the area where black knights are found.
Cannon should also work as intended inside corp cave.