I cannot open the drawing to see what you are doing, but sloped rails are done all the time. They have to parallel the walking surface they are built on, and must be at specific heights by building code restrictions.
I am pretty sure the real world physical conditions and AutoCAD parameters allow the possibility of a railing that veries in height, curverd or otherwise. However, the building code sanctioning bodies in most US jurisdictions would have a cow over it and make you tear it down. Another possibility would be to build the decorative railing at any height or configuration you wish, and then install a handrail along side of it that meets code restrictions.