Most of a generator's properties can't be evaluated on a per-spline basis since internally they are processed just once before the geometry is built. There is however a workaround that circumvents this if you don't mind nesting generators.
Please take a look at the attached. It uses two A2S generators, one nested inside the other. The nested generator gets its height, width and evenly distance by accessing the main generator's properties using dot syntax, for example, assuming the end generator is called MainArray you could access its Y size using return MainArray.YSplineLength;
I hope that helps,