Now, after caroleans were nerfed, swedes should mix their units, but the problem here is that one of the units that supposed to be mixed with caroleans just broken.
Leather cannons move like full-sized artillery, that not only looks ridiculous (because their model 3-6 times smaller than the other artillery) but also makes it almost impossible to keep them alive in a fight. I think LC should be just a stronger and slower version of the abus gun and should move like ranged infantry, not like artillery.
Also, their price, 400 resources for such a fragile unit is a bit too much. It almost the same as an organ gun (20-25% cheaper if considering gather rates), but organ gun times “tankier” (0.75 vs 0.5 resist), better and more useful than leather cannon. 2 LC from the shipment is the only LC you will see on the battlefield in most of swedes games, just because building them in age II is the easiest way to through away your resources and lose.