It would be interesting to know why you thought that a JAA licence needed a conversion to an EASA licence in April 2012 - an article? a bar conversation? an instructor? Personal misinterpretaton of something that said otherwise?
I remember in 2000 there were some interesting 'interpretations' with all the new JAR changes - I wandered into one club and found an announcement saying all their members must book to do a session of three circuits every 3 months with their instructors to satisfy that 'JAR 3 month rule'.
Nice money spinner at first until they were rumbled by the members.