Dear Alex,
Nice to hear from you again after a long time.
I hope you are doing well down under.
Thank you for your query, and many thanks to Thomas for his helpful point.
If Revit does not support full-fledged curved sections OOTB, then you cannot create them programmatically either.
However, you could perfectly well create something quite similar yourself using the API.
The most difficult part to achieve might be full associativity.
However, it sounds to me as if you can save thousands of hours by creating them programmatically.
Also, you presumably have a pretty clear spec on what you need to see and what not in your curved sections.
Obviously you can draw a curve through the model, use that API to determine what is located vertically above it at what point, and represent that in a useful way.
So, I would say yes, you can probably programmatically achieve what you need, or at least the most important aspects of it.
I hope this helps.
Best regards,
Jeremy