Fair questions, really. They truly are. Ones that I believe we both can safely agree that neither of us have the answer to. However.

[ helen nods to the room around them. ]

The easiest solution would be that all of these books are counterfeit. A collection of oddities over the time to easily fool people. Perhaps the former owner found them around the globe.

Of course, I haven't ruled out the more wilder theories that spring to mind.