This is an easy fix and I think it’s important to restore children’s books as much as possible. I was able to color photocopy the final end pages. Then I sprayed the copy lightly with matte acrylic spray to give the page a little more strength and dirt resistance.
Trim the page to a 1/4″ stub using a self-healing mat or other protection.
Dry fit the page on top of the stub. You can trim the top and bottom of the page now, but leave the edge of the page till later.
Insert waste paper under the stub and apply glue. Attach page, protect with waxed paper on both sides and set a flat board and weights. After drying the right edge of the page may need trimming.
A satisfying repair as it is invisible unless you inspect the back of the page!