8 – Multiple roles in access to the work plan

I use D8 Workflows and Workbench Access. There are two roles: authors and proofreaders.

I've configured workflow permissions so that authors can create new pages across the entire site and use the Draft transition for review. Reviewers can use the transition from In Progress to Approved.

My goal is to assign reviewers sections using Workbench Access. They will be the only users able to use the Approve transition.

I've set up Workbench Access to use the taxonomy and reviewers assigned to their sections. I've added the Author role to the root taxonomy so that they can create pages anywhere.

My problem is that now all authors have access to all workflow transitions and it seems that workflow permissions are not enforced. I need Workbench Access to limit the sections that the Reviewer role can modify. However, all reviewers are also authors, so they have full access.

How to use two roles for the same user with different permissions per section in Workbench Access?