Hermitage needs three pieces of art for theming bonus. Artifacts are fine for museums (and other GW slots).
I think that is a mistake. First two GW should go to Oxford for theming bonus. That is 4 cpt before bonuses, and it runs for most of your game. Early treatise are few hundred culture, not thousands!
I am not convinced that CV goal really changes the GW slot / bulbing equation. For CV, one is aiming for Louvre, but that is only two more GA needed for theming bonus. Even for CV, I think most Great Writers and Artists are better being bulbed.