When I initially assign an Administrator Role, the existing permissions are not assigned to that role. It would be helpful if all permissions could optionally be assigned to the new Administrator Role. Example:
I have confirmed, that using the method $form['#attached']['js'] stops the webform.js from loading.
https://docs.backdropcms.org/form_api#attached shows that this is the expected method of JS loading...
Sounds like a valid feature request.