See the list of abbreviations in LASORS....
(Including where they've porked up ADF, AFI and AIC!)
FI(R) most definitely is listed.
Unless a 'UK Flying Instructor' has signed the 'Declaration of knowledge', he/she cannot instruct for a JAR-FCL licence or rating. By now everyone must have revalidated or renewed their FI rating to do so, so what exactly is your point? If you're a current FI then it makes not the slightest difference whether you qualified as a Flying Instructor under the old scheme or as a Flight Instructor under JAR-FCL. Whereas their is a difference between an AFI and a FI(R)............