The Lost Omens World Guide says the Worldwound was closed in 4718 AR. I was under the impression that this happened earlier, sometime between 4713 and 4715 AR.
It now looks like the campaign to close the Worldwound, the combined efforts of the heroes of Wrath of the Righteous and the 5th Crusade, took five years from 4713 to 4718. It also appears that the first major event in this campaign was the failed demon attack on Nerosyan, shown in the PFS Special - Siege of the Diamond City. Is this more-or-less correct?