Struggling to Understand Offset Curve on Surface problem.

Hello everyone!

I am struggling to understand why an curve that is being offset on a surface would do so in the wrong direction and with a shorter length than the original curve?

The surface is double curved (Hypar) and I know this presents challenges with planarity, which curiously I have previously solved in the definition called (hypar jagged surface) inside the .gh file below

The challenge lies when I try to recreate the same solution with for multiple hypars. which is odd.

Any ideas? Is this an issue with rhino?

Thank you