There is now a canon example. A human skull reshaped into the form of a book's cover retains both its shape and material bonuses, not just its material bonuses, even though it is no longer in the shape of a skull. So it looks like in canon changing such features does not change the associated bonuses.
So a thing that has not a certain shape can have that shape.
Right.
Still it can be OK if it does NOT have the shape bonus for "book cover" shape. I could accept that. If it also has the book cover shape bonus, it is not acceptable IMS.