You could rivet the awning to the roller, but you would have to be sure it was definitely in the right spot first. I am not even sure it will move, as ours has shown absolutely no indication of doing so.
As for the bumps in the rolled-up awning, ours does that too, and I think it is just from the cheap awning fabric stretching more in the middle than on the ends. And actually, that might have something to do with yours not rolling up straight.
One thing for sure, the awning material they use today is garbage compared to what they used 15 years ago. Our old fifth wheel had zero problems with the awning, and it was still good after 15 years of use. I seriously doubt the new one will last that long!