So FGO(TW) just announced that the Interlude Campaign 16 will start on the 18th and end on the 25th. If TW was following the JP schedule, Nero Fest rerun will be next, which will put you in the 2nd week of May, just in time for the anniversary on 5/13. But it's already confirmed that the 2nd part of Avalon La Fae's main quest will open on the 25th, so people are speculating that Nero Fest might be delayed to sometime after the 6th anniversary and LB6 Part 3.

I don't know if NA will follow the same pattern, but this is a pretty big deal if it does. Being able to farm LB6 material will allow you to fully level up skills for Morgan, and we are looking at Melusine, Vitch, and possibly Oberon getting released before Nero Fest, which could completely change how people farm the box event.

It's also a big deal for anyone who is planning to LV120 their servants since you will be able to use all the embers you farm from the Nero Fest(On JP, there was a 2-week gap between the end of Nero Fest and the start of 6th anniversary.) You are also looking at up to 3 extra grails available that weren't available on JP at the time (2 from completing LB6 and 1 as an anniversary gift), which could help your progress towards LV120.

We don't have confirmation yet, but I just wanted to throw this out there, since it's very unlikely that they will be running Nero Fest and LB6 Part 2 at the same time on 4/25. I guess it's possible that Anniversary could be delayed, but then again, that seems highly unlikely either because it's always been on 5/13 on TW. It also makes sense because this will give more motivation for people to farm hard on Nero Fest to get a head start on their first LV120 project.