An AFI rating is a whole separate thing, with different requirements to be met before you get a full instructors rating
Since 1999 the requirements for an AFI to upgrade are exactly the same as an FI(R). A number did not achieve this and some have returned to instructing so there are a number about.
Under EASA its not for the CAA to provide guidance any more. ATOs will be required to specify in their manuals what is required and in the meantime RFs will be able to decide as they wish however; it would ultimately be up to a court to decide if their interpretation of supervision was appropriate if there was an accident involving supervision.