How about a new museum perk ( could come under jewellery or pottery) that reduces upgrade times. Need not be much, maybe max upgradable to 10 or 15%, could also be super rare to find. It could also be specific instead of universal - some giving only library/ University reductions, some only defensive building reductions, etc etc.. That would generate a lot of interest in the museum. People would also be willing to spend crowns on museum supplies/blueprints in order to max out the artifact