Hello Fei Hua,
Thanks for the explanation and the screenshot.
Yes, I understand your idea. This is a slightly different feature from the Path position mode that we have just added.
The new Path position mode solves the case where the same parent path is repeated through several levels. In Across all levels mode, the Path position value is calculated continuously across these repeated levels, so the curve does not restart from 100% to 0% on each level.
Your Curve Range node idea would be a more general utility node. It would allow taking only a selected part of a curve, for example 0–50% or 50–100%, and remapping that part back to the full 0–1 range for use by another Affect node. This could be useful for manually sharing one curve between several paths or several Affect nodes.
We'll look into this idea for a future update.
Thanks again for the detailed suggestion!