I've only had my J pouch a few years and the surgery itself has been a success, although I still endure some associated issues but my UC is in the past.
I've never experienced the dreaded butt burn either.
As mentioned, I've had my ileostomy for quite some time and before my J pouch creation, no one ever suggested pelvic floor exercises to retain control, so never done any; so maybe such an exercise is not really necessary, unless there's a difference between the sexes.