I don't know much about the durability of the cutting and gluing, BUT...............
I DO know that Walnut is a beautiful American wood and while plentiful here in the U.S.A., it is a great tone-wood. I have a multi-laminated Walnut '79 SG that is a great sounding guitar.
I love those J-15's for the value and buyability and bet some of them sound exceptional.