It may be “a permanent injury that will never go away”, however, you can improve your experience with mobility work. I was told several things from an accident would never change, however there was change and several are in a better place than pre accident.
From Episode 11
“Your body is one constantly adapting system. It has the capacity for
change at any age or situation. Your machine is infinitely sensitive to
change and will always just reflect whatever you throw at it.

Take home: You can always improve. Always.”

If you are working on things and not seeing change time to take another look at how you are addressing it.
Are you working up/down stream from where you are seeing the issue?
Pro Episode # 21 – Pro-User Request Friday: Not Seeing The Change? You Need a Systems Approach.
A couple to start with:
Start with addressing internal rotation
The 500th Video; Great Sub-Scap Shoulder Smash Drill
Episode 297: Liquid Kayak Camp and Lat Hell
email me [email protected] and I’ll send you some additional ways to address it.