> The difficulty in fencing such extremely rare items must be immense.

It's probably similar to other underworld industries, steal-to-order is definitely more common than what people expect.

I dunno if this was one of those, given that the books were apparently stashed under a floor for all this time. Makes me think it was a speculative theft but they couldn't find buyers.

They might have been waiting for waters to calm down. 3 years is not that much time to wait, for objects of this rarity. In fact, they might have planned to keep them for longer but for covid19 forcing their hand (the black economy must be currently struggling in the same way as the regular one, of course).

He he, the irony. Transylvania is a Romanian region :-)

I don't get why this is downvoted, it's a funny coincidence :-)