Hi,
If I understand correctly, the problem is that the ChangeWidth node is not affecting the hair width in the render. right?
If so, I noticed that you are rendering with Redshift, which at its current version has an issue with the ChangeWidth node in Ornatrix. We informed the Redshift dev team about this issue and they are working on a fix. Keep an eye up for a Redshift update soon.
Jeordanis Figuereo (Product Designer. EPHERE Inc.)