Carolean is just a broken unit in general that needs a nerf, strelets are fine as they are any buff to them would make them too strong against other civs.
What sweden needs is a change to svea to remove the range resist, 25% extra hp is enough. Infinite 6 mamelukes needs to be changed to just a 1 time card or infinite 4 mamelukes. The charge ability needs to be adjusted because it’s what enables caroleans to so easily beat their counters or other musk in age 2 without it they’d be much less effective.