I thought it was established that time travel shenanigans happen WITHIN the designated 616 universe, not in a separate universe. Although maybe there is a parallel universe out there that mirrors one of the past timelines.

I suppose its possible that any given story that doesn't explicitly say it takes place in 616 takes place elsewhere, but how often has that happened with a mainline story as oppose to something being explicitly alternative. When you get a something like time-travel by reincarnation to explain the differences you are seeing, isn't the easiest explanation that it is in the main continuity and the explanation its the 10th timeline of potentially 11 separate timelines, exactly as Moira describes it to be?