Multiple extrusions/sweep question for gear generation

I'm attempting to port my gear generator from openscad that can produce arbitrary helix patterns, like this:


Getting the general gear profile generation working was simple, and splines are awesome:

But I'm having a hard time finding a good solution to set up the helix generation.

I would expect to be able twistExtrude multiple times (`p=p.wire().twistExtrude(5,20).wires(">Z").twistExtrude(5,-20)`), but there's something I don't understand because this just errors out. How would I extrude the top face of an object?

I had a little bit of success with sweep and an auxSpine

That's very satisfying, but trying to define a herringbone profile with a polyline as the auxSpine just does strange things

Source is here: https://github.com/wentam/Compound-planetary-gearbox-generator/blob/db55c7ff6a5a3625f614d7179e7d08a9f393230f/test.py

I'd any appreciate ideas on how to best solve this!