We need to have a discussion on the two topics above.
For guests, I am of the mind that they can stay in the quarantine area and never be let in to the Covenant proper. This is because we have no way of knowing if they are carriers ( yet). A non-gifted person has no way of knowing if they are a carrier.
For books: The Ownership must always be retained by the person who brought the book. If any wish to gift the Covenant with a book that is their decision. If the owners want to put them in a central library, that is also fine. But because any of the magi could be removed from the Covenant proper, they must have ownership over what they have brought.