Might want to give the crossbowmen a shield of some sort. Italian crossbow mercs were (rightly) feared throughout Christendom because they'd found a solution to the main problem with crossbows in missile duels, namely the long reload times.
What they did was, they wore huge shields on their backs. They'd shoot, turn around to reload, then turn back to shoot again. So the only time they were vulnerable to counter-fire was when they were shooting, which obviously wasn't a good time to be anywhere in front of them
. When they didn't expect to have to move a lot around the battlefield they'd just stick the shield into the ground and ducked behind it, like a portable fortification of sorts.
Pavise shields were of course en vogue throughout Europe by the time the Renaissance swung around, but nowhere near as much as in Late Age Italy. Dudes loved themselves some crossbows.
I think it's also the Italians who came up with the claw-and-stirrup system (a hook worn on the belt, and a stirrup at the end of the crossbow, to make reloading easier and faster by using the leg muscles instead of the arms' or a windlass), but then again I'm not sure a crossbow firing every turn would be all that balanced
