I was under the impression that when an FI upgraded to be able to teach MEPs they actually were getting a CRI rating
That has not been the case in the UK. Teaching ME is one of the privileges of the FI(A) rating, subject to completing the ME CRI course and test.
My UK licence says: FI(A) SP SE and ME and my JAA licence says the same. I did have the qualification pre JAR and CRI ratings.
There is no clarity in any of the documents, so it is easy to see how the confusion arises.