There are a few books scattered around the library that give very basic instructions on how fae magic works; think of it like science books for an elementary school student. This will certainly be enough to get her and her crew a chance to start tinkering and experimenting with the tech, though.

Rikku will also find hints that something about (or within 👀) the castle powers all the magic in the Realm of Faerie, but what or where it is will currently be harder to track down. Tucked away in a corner, there's also a simple picture book, a children's work of fiction, that she might stumble upon that describes what would happen if someone were to mess with this source of magic (beasts going crazy and attacking, and general discord among the fae populations), and an ancient feared shapeshifter who's known to wreck havoc called the Fate Bringer.