The biggest issue for the shoulder is usually, when you reach for the ball instead of getting into the right position. Than you need to extend the upper arm, which is an additional lever for the weight, stressing the shoulder joins.
Trying to get in front of the ball and waiting for it to enter the strike zone is key, then there is only limited impact on the upper arm and shoulder.
Easier said then done, I know this very well. I try to improve my backhand since a year and improving the footwork part is damn demanding

.
But treat your shoulder pain as a sign to work on these topics.
Blade balance however is very important for BH/VH transition and impact on your wrist. My setups are usually around 200g and I needed to rebalance the blades, because otherwise I would be to slow with the transitions and the spin on the BH would be less, as my wrist acceleration would be lower with the head heavy setups.
Head heavy helps, because it is then much more natural to drop the head for the TS motion, but you need the strength then to accelerate the head again. Which is OK for top rated players with their training time, but us mere mortals might struggle with this (especially if you have a desk workplace, where lifting weights

with just our hands is usually not required).