Sorry, I meant the claim that the sculptor not knowing how to make the back half. I definitely believe you on the name! That wiki page isn't available in English but I translated it and only found this:

The legend[Which?] says that this square is made up of four elephants without backs since its sculptor did not know how to do the back says the "ass" of the elephants. This is what would have given the name of the 4 without asses.

I read about the construction elsewhere and only having the fronts seemed deliberate