Hi,
Thanks for the question. I've attached a sample file for you to check out. In addition to the changes mentioned, I've changed the approach a little so that you can more easily control the X/Y spacing of the beams and columns since it it quite hard to get them in a realistic position when the building footprint is not rectilinear.
In this setup we are combining clipping splines with the X and Y spline. To position the beams and columns you simple use the RC Spline modifier to add markers to the X and Y splines.
The only limitation of this approach is that the RailClone object has to be at the world origin. This doesn't affect the actual position of the building, but the RC pivot needs to be at 0,0,0 in order for the various layers to jigsaw together correctly.
I hope that helps, please let me know if you have any questions about the style,
Best,
Paul