I think I have an idea of how to do the bridge scene in a natural way (although you’d need some FX shots)

The scene happens like normal up until Kylo drops his mask. Then we see close shots of him drawing his saber and obviously preparing to kill Han. Chewie notices and shoots Kylo with the crossbow. Kylo is blown across the bridge by the crossbow as he ignites the saber. Chewie sets off the explosives, and the rest happens like normal.

It’s still not perfect, but better than Chewie firing for no reason.