The Lost City of Amdaphor and the Sineaters

[Kalise]

I just want to pop in and stress again that "umbral aether" and "Light" are not the same thing and debating under that premise closes a gap within which important nuances might or might not lie. In the transcripts and game materials that I've read/saved/remember so far: Number of times explicitly umbral aether / umbral energies are mentioned in the same breath as sin eaters: 0

Might want to pop back and check the explanation Urianger gave in Il Mheg in front of the MTG chart.

I'm fairly sure he mentions that the "Light" is Umbral Aether (While having slightly more authority on the matter being more of a scholar than Alisaie)

It's in the cutscene when you first meet up with him (Alas, due to that, I cannot easily bring up the transcript)