If you have a look at your library inside Visualize and navigate to:
Library > Cloud > SOLIDWORKS Appearances > Plastic > Textured
you'll find appearances named "pw-mt11xxx" which I assume are Mold Tech appearances.
Apparently they all seem to share the roughness value of 22.16. But there's still some difference in surface roughness between them as they don't all share the same normal map or texture density.
Normal / bump maps affect surface roughness as well.
Hope that was of any help.
Would you be willing to share a real photo of your product and a rendered image? You might be able to get some better input and ideas from the responses.