I think I remember reading years ago that it is not a matter of disrespect to call the Pope by his sir name....Bergoglio. It is rather a matter of custom. And a longstanding custom in certain areas, especially Italy. I can't find the particular post but I think it was explained on Fr Zs blog. Is anyone on this forum familiar with this custom?
I've read that it's fairly standard in Italy although I understood that they would usually say "Pope Bergoglio".