Generating a path from selected point to the beginning of spline on a closed spline?

[_Aka_]

The range variable was not applicable because the Spline could not be clamped for the end/beginning of the loop, so it did not work the same way as it would on an open spline.

If I am not misunderstanding, you could have two Shape Extrusion modules both with ranges, one from say 0.8 to 1, the other from say 0 to 0.3.
Even though your modified module fits properly your needs, without having to have two Shape Extrusion modules, please let me know if what I suggested is an alternative solution to your issue.
Thanks a lot, and have a nice day