I’ve added a small feature to 4.1.82.
You can pad numbers with F function. For example [=F('{QUANTITY}','{0,2}')] will pad quantity value right with 2 spaces. You can pad it to left with negative values. I know that won’t work flexible as justify feature but it might look better at least for double digit numbers. <J> tag will align first column to left and other columns to right as we generally use it for or values. I’ll try to improve that on next releases.