The business with Elune does make some sense, but it also requires you to make a whole bunch of assumptions the game has not told oyu about.
The let Teldrassil burn because she did not realize Sylvanas was allied with the Jailer. She sent the souls to Ardenweald not realizing the Jailer was already active.
She didnt let Tyrande kill Sylvanas because it would kill her, and therefore prevent Elune from contacting the Winter Queen.
The game really should not require this many assumptions without at least giving us something substantial to work with.