There should be paintings for the museum, even though there are paintings all of them are frameless and broken. You can still keep them, but it would be even better if we actually got more works of art maybe in the old days of Raven Brooks maybe it would show the Mayor shaking hands with someone, and other works of art, etc. It seems weird that the Museum doesn't have any paintings the only actual paintings it has is the Forest Protector portrait and the painting in the entrance but it kind of makes sense that the paintings in the Museum don't have any photos maybe they all got torn off for some reason due to disrepair or something. But also this applies to some houses as well, most of them are frameless (although Patch 9 did add a lot of actual pictures in most of the AIs houses) The Neighbor's old house barely has any.