Hi Hans,
You can do anything you want, it’s just a matter of how much work it would be. ?? You would have to modify the core of WC Vendors to change the name of the Vendor role to something else, and then change all the calls to it where needed. And then when you updated WC Vendors to the next version, you’d have to do it again……….
You might look into a plugin that assigns TWO roles to a vendor, though, as WordPress does allow this. Then you can keep the Vendor role and the other role you want the user to have. There’s a few dozen plugins that do this all free on the WordPress repo, just have to sort through them to find the one you like.
Ben