You are right, The Realm of Dreams Quest does not show up in the quest log.
You could check the top of the Draconia Black Temple to see if you can take the Key to Magic book from the chest there. But I honestly dont know if that resets, especially after so long.
Other than that, if you have access to Chayennes key, you could simply try the quest again. Though to be fair thats not the easiest thing in the world to do. Good luck.