Record owner role

Before the record is saved the first time, the record owner will not exist, so you will have to just check the current user role. However, even when the Record Owner exists, I do not think there is a way to check the role of a user in a user field.

I've done this in the past by having a formula field to grab the role of the current user, then using a dynamic form rule to capture that in a text field when the record is saved. 

It may be possible to do a GetFieldValues/GetRecords formula if you set up a connected table to the admin console to show users and their roles, but I haven't tried that yet.