4/29/19:
So, I've been asked to clarify some plot points... we had three different Rosie time clones running around at one point. Evil Rosie (from the Necromancer's closed time branch) was killed by Future Rosie and Present Rosie (in Episode 952). Future Rosie (who, along with her husband Bart) showed up in the present during the Quidditch World Cup arc. They came from a future where most of our heroes were killed by terrorists when the World Cup was bombed and the Necromancer had won in the chaos that followed. It was the Future Rosie that was killed by the artillery shelling in recent episodes, leaving only the original now alive.

In other news, if you somehow haven't gone to see Avengers: Endgame, go watch it! (And post absolutely no spoilers about it or anything else on the tagboard.)