She creatively hid the mistake in the center. She quilted from the edges toward the center, which then "trapped" excess material.
About the only thing I can think to do would be to remove the center to get rid of the excess fabric and cover it with an appliqued piece. Perhaps the Hansel & Gretel could be appliqued to a background piece, which could then be stitched to the center. The center could then be hand quilted.
But is it worth that much work?