Thanks! I just updated the art package to contain the missing files. I think I got everything now.
So uh, I downloaded the update, and the Art Pack is the exact same as before. All the Doll Types, Stranger, Pygmalie, the Doll TFs, some endings, the sketches, and the main characters.
All the other sprites are still missing. I even deleted the artpack and had Steam install a 100% new one and it still didn't change.