first, your statement makes no sense, as the x axis is left-right, not up-down. Second, it is intended to be "backward." Many co-ordinate planes use this notation, not the stuff they teach you in Geometry A.
If you just wanna use ghost pieces, and don't wanna use FCML, just edit an original ghost level. You can't change the piece sizes, but you can rotate them. Find a level with a lot of gost pieces and change the url to "edit" instead of "level"