BabaJ

What I was showing you is but one step if you wanted to use the carve sop.(I thought you would be able to see the other steps).
Just calculate your total distance for the entire segment, get the ratios of each individual segment per total length, which will let you know what 'uv' distance each segment is. From there you can carve(with the sop)the specific segment in which your target uv is lying.

To build something around this in order to mitigate that behaviour would surely negate the slight performance advantage the carve node has, right?

How do you know the carve sop has better performance when it's not doing what you have with vex?
Did you try comparing a single segment with vex(only two point ends) compared to the carve sop?

I'm assuming the issue you're having is when using the carve node on a polyline.
Perhaps you could run that line through a convertline node - and then apply your carve node per prim as needed, reforming back together your single polyline after you get the desired shifts.

https://www.sidefx.com/docs/houdini/model/aids.html [www.sidefx.com]