@Shpco You are not being long winded at all! Yes it is normal for the new shoulder and arm to be stiff even 6 weeks after surgery. Both of mine felt stiff and tight for over 3 months. And given the problems you have with spasticity on that side it will probably take you that long or longer to get the maximum functionality with this shoulder. You might check with your surgeon to see if there is a different muscle relaxant you could try.
With each of my shoulders my out patient physical therapy did not even start until 6 weeks after the surgery!
Also have you ever tried getting a massage? Perhaps your PT could do some massage before doing exercises or movements with the new shoulder. Also if your PT person does not have experience working with patients who have had a stroke you might ask if there is anyone at that facility who does have such experience.
My mother in law had a stroke and partial paralysis on her left side and when she went for PT following the stroke she was assigned to someone who had extensive training and experience -- and it did help her quite a bit.
I hope your recuperation will progress smoothly!