Ηi Eric!Thanks for the info, Chris. Added to the community wiki and will also soon appear in the Card Sleeve Sizes for Games.
The card sizes of When I Dream is as follows:
-64 Dream cards will need 80x120 sized sleeves (dixit size)
-11 Spirit cards and 2 scoring cards will need 63x88 sized sleeves (Magic the gathering size)
Thanks a lot for your interest!