I love a good library adventure, and the art and general vibes of this adventure are absolutely great. My primary critique is that it is hard to visualize the layout of the library, and the quantum nature of the encounters (wherever you go, you find a clue) does the exploration of the library a disservice.
I would have liked a map with concrete encounters in specific areas. Not only would that make it easier to run, it would make the library easier for the players themselves to visualize.
I love, love, love that the reward for completing the quest is essentially a library card. That makes my heart happy.