When she first arrived, Beverly was a little bit forgetful and left one of her quest items behind. This should be fixed as of September 2021!
You should be able to find the second acetate Beverly asks for in Old-Central District on top of the apartment building to the far left of the island. You’ll need the Bounce ability to get to it. If you opened this chest before Beverly asked you to, then the item should already be in your inventory and ready to go for her quest!
Simply visit an island to trigger Beverly’s move to the acetate room, then go and project Henry, 8 Years Old.
For visual reference, here’s the chest: