It's not really 'new' in Italian, it's a simple matter of applying the stra- prefix, meaning to go beyond, to any adjective. The product is a kind of hypersuperlative if you will. I can see a few uses online of stralimitato from earlier years, not by the Pope. Which by the way is the same word but with a masculine ending.
He struggled for a moment to find the right word to capture his stop in New York. According to the Associated Press, he just ended up inventing a new one: stralimitata. "In New York, a bit 'beyond all limits.'" The New York Times translated his quote as, “New York was a bit exuberant."