What are the characteristics of a flip card in my library?
In your library, a flip card has only the characteristics of the top half of the card. You cannot use Enlightened Tutor to find Sasaya, Orochi Ascendant, because


  In every zone other than the battlefield, and also on the battlefield before the permanent flips, a flip card has only the normal characteristics of the card. (CR 709.2, emphasis added)


(From 709.1a and 1b, the top half defines the "normal characteristics", and the bottom half defines the "alternative characteristics".)

Basically, until it's actually flipped, the card/spell acts as if the flip version wasn't printed on it, so neither the tutor nor the enchantress will ever do anything with it (since it's not an enchantment either when you cast it).