substeps and resolution of the wire influence the stiffness indeed, but there should exist a specific attribute for it, like there is for the Wire Solver: it's the @targetstiffness attribute which
“defines how strongly the wire resists deforming from the animated position”Also, @targetstiffness can be used for Pop Grains too, so I really don't understand why we can't use it for Vellum as well, which is based on grains.
There must be something that we are missing about setting up the point attributes for Vellum?
*EDIT*
I was probably making some confusion.
Regarding the stiffness you should modify the stiffness parameter under “Bend” in the vellumconstraints.
It seems that it doesn't read the per-point @targetstfiffness attribute, and it's more an overall general stiffness value for all the points. Am I right?
The main problem for me is that if you pin point 0, the wire fall down and pivot around its base pinned point , there's no angular constraint. So we must set somehow the angular constraint I guess?