Thanks for the suggestions. Unfortunately this is a limitation of Adaptive mode which expects all the segments to be of the same size in order that they can be scaled to fit the path accurately. Due to the order of operations it isn't possible to adaptively scale segments of different lengths.
The usual workaround is to prepare the geometry so that they are combined to form segments of the same length on the X axis. You can see examples of this in this façade post
You might also find Chapter 2 of our Next Steps with RailClone guide useful which mentions this limitation: "If you use default segments with different lengths and adaptive mode, you could find that the final segment sometimes overshoots the ends of the path. The Adaptive algorithm is only able to accurately scale the meshes if they are identically sized on the X axis, so if you plan on using this mode with multiple segments, ensure they are all the same size." You can read it here
I hope that helps.