Quote Originally Posted by arstoka View Post
That makes a lot of sense and I appreciate the clarification since the story tends to leave a lot of gaps in places that can only be understood retroactively.

My one concern is that...the 12th shard was the calamity of lightning and thus was absorbed through the 2nd umbral calamity. As for how the timing works on that...your guess is as good as mine (unless I'm misunderstanding the lore here which you should feel free to correct me if I'm misunderstanding).
I think we have way too many unknowns at this moment. I don't think they even confirm their reflection is the 12th Shard, but that is what makes the most sense given the evidence.

There's also the fact that we don't know how time dilation affected their shard. There's thousand of years in the Source between the 2nd umbral era and the 5th umbral era (when the lalafells crossed over with the key), but it could easily have been 5 minutes for the Alexandrians point of view if the writers want that to be the case.

Presumably Sphene-bot had spent a long time rebuilding her realm by the time the lalafells arrived, and the dome could have been erected to shield them from the 12th shard rejoining... But we just don't really know.