Hey thanks!
In terms of the gallery item, you should have the Key Item called "Ankhrono Replica" in your key items which you receive after beating the Forest Path's boss. Unless something weird happened with the coding this item should still be there. You'll use it and get teleported to a different area where you'll walk left to get to the gallery area. It requires you to defeat the boss of the corresponding areas in most cases to unlock the sprites and scenes that are available.