As I am copying workflows for new communities in the content explorer I find that the workflow is based on another workflow but the roles are changing. I think adding a “Replace Role” button next to the “New Role” button would be helpful. The button would act like the “Copy Workflow” button in that you would choose which role to copy from a dropdown list and choose the new desired workflow role from another dropdown of available roles. The new role would then replace all instances of the old role in the workflow and retain all attributes for each transition within the workflow.
After you copy the workflow you should be able to click on one of the role names and that will take you to a list of role names. Selecting one of those roles should replace the old role.