While the original, and most straightforward, interpretation of the end of Convergence was that after the convergence team disrupted the crisis, the surviving worlds became the current multiverse, I choose to interpret it a little more abstractly: I take it as an indication that while the original worlds still exist, they were not unchanged. It's in accordance with a principal that I hold, that the older a story is, the less reliable the details are. So the boat May well have happened; but it probably didn't happen precisely in the same way. Little things like “quiet, or papa spank” are unlikely to remain true, even if the main story beats do.
More generally, my take on “Everything Happened” is that you shouldn't take it too literally; they mean that the overall story of the Metaverse all happened, not that literally every story ever published in the Metaverse really happened. There are some stinkers that I'm sure even the most ardent supporter of the concept would have no problem excising, such as the Bronze Age story where Superboy became Superman by sleeping with a girl who was being mind-controlled. (There was a waiter on Superman around that time who was rather misogynistic.)