Among thoracic surgical procedures, plication of the diaphragm is not rare. I was able to find numerous reports of series in the 20-30 range, some with long term follow-up. With a proper candidate (for this procedure) and a proper selection process, there are many reports of outcomes similar to yours, 5-10 years after surgery.
The key for a patient contemplating this procedure is to first have an evaluation by a (non-surgical) pulmonary specialist to confirm that the indication criteria for this procedure having been met the likelihood of a good outcome is high. Second, I would seek consultation with a surgeon who has had experience with the procedure and data showing good outcomes.
I am delighted to hear of your good fortune, with this surgery.