This is from silver flames after Nesta helps Gwyn.
"Some philosophers believe there are 11 worlds like that. And some believe there are as many as 26, the last being time itself, which.." Gwyn's voice dropped to a whisper.
Time travel might happen in the acotar. Gwyn might know about it.
We find out later that Merrill believes there are 26 worlds.
The harp has 26 cords.
Koschei is definitely involved. Could he drag two couples back in time before the daglan.
To stop himself from being trapped.