Exactly what we did...peened the other side. It was optional but nerveless did not return to original shape.
The intensity was within the allowable range as was the arc height measurements and calculations.
The part was to thin and that is why masking was required in those areas but only required on one side of the part.
I personally haven't seen that requirement before. Just makes sense to me whatever you mask and peen on one side of the part should be done to the other. Process design is checking into it. I will let you know.
Thanks, Shotgirl