The role management was completely renewed for OJS3 and you are definitely on a good way here. The division into stage assingment and permission level probably makes sense, but unfortunately the latter lacks on documentation. I can guess that the level names correspond to the old OJS2 roles, but what exactly can for example a Guest Editor do? Why does the help page mention Series Editors but not Subscription Managers? A revise of the documentation regarding this point can probably help users a lot.
In addition I want to request a new permission level which is located somewhere between Reviewers and Section Editors. In our workflow we have Review Managers who control the complete Review including the Assignment of Reviewers. The crucial point is, that they don't make final decisions on the acceptance/decline of a submission. They report the outcome back to the Editorial Board.
Currently we have to use the SE role for these Review Managers. Here, finishing their part of the review means sending the article to copyediting and informing the author about the decision. This stands in direct contrast to what our workflow suggests.
Similar things have been requested before under names like SE Recommendation and SE Final Decision Option.
Hopefully we get this running. It would be a pity, if this minor limitation stops us from using this otherwise well suited software.