Hi,
First let me mention, that stairs can be tricky to solve within one style as depending on its design, it can bring several problematic places.
As in your case vertical spline segments are causing unwanted artefacts, I would suggest you to remove those (& move the lower part of spline to have a continuous line). To avoid Start / End Segments I've welded some vertices and for the "Glass handrail end01" Segment set Deform - Flat Bottom to 0,0 m. Attaching modified scene. Hope you'll find it useful.
Best regards,