EDIT - ok now I have read it all… not sure what you mean by “roll forward”. can you describe it differently? This is possibly/probably a key thing here…
btw I’m a 2nd year DPT student and just finished a lengthy shoulder diagnosis part of an orthopedics class so this is actually some good practice for me, thanks for posting
The roll forward… If I stand and put my fists on my hips, chest out, shoulders retracted, upper arms/elbows pointing straight to the sides, my left shoulder will be back, lined up as it should be. The right is different. That shoulder is rounded forward slightly, and if viewed from the side (the sagittal view, to you medical types), you can see that the upper arm is not in the same plane as the body; the shoulder is forward of the elbow (the upper arm points backward toward the ground).
If I pull hard to get that shoulder no longer rolled forward, that upper arm is now pointing well behind me. So if I lean forward and look into a mirror, my shoulders will be in line with each other, but to get there, my right arm is now pointing straight behind me while my left is still pointing out to the side. In other words, I cheat to get to that position by internally rotating my right arm less.
Going back to standing, hands on hips… If I then put that arm behind my back, I can get there no problem, and in fact I can touch the scapula on the other side. BUT that right shoulder has now hunched/rolled even farther forward for me to get there. If you looked at me from above in that position, you would see that right shoulder well forward of the left.
Here’s another way of describing it. Laying on my back, arms externally rotated up as if being robbed. Both shoulders are against the floor. On the left side I can internally rotate until that forearm is about 30 degrees from the floor. The back of the shoulder stays firmly against the floor to that point. On the right side, that shoulder comes up off the floor at about 45 degrees from the floor, may be even higher. And if I press that forearm further, the shoulder comes even further off the floor.