“these errors are thrown from pages that role R doesn’t have access to”
You can right click on the page containing that error, and click on find usage(or ctrl+alt+f), you will see a list of elements that is calling that page.
Probably for one of the element your user role R have access to it.
It may also be a problem inside the security, in the user roles tab, if you mixed up the role (for example if you said that the user role R of your application, is the user role A of the module containing the page)
Hope this helps