Seen and answered ;)
I'll copy it all here for anyone that is just reading Itch.io and not also FB.
Question:
Does each player take a turn playing Cerin and then decides to Tell or Wonder? Then pass play to another player who also chooses between Tell/Wonder? Then the endgame is triggered when all the Tell questions have been answered, followed by one more Cerin Wonder play? Do I have that right?
Answer:
Yep :)
You got it right.