Bleeds off - my understanding is that you just trade your own 'national ATPL' for a JAR one in your home country. In the UK it is a reasonably painless (but not costless from what I recall!) process. At that point you are deemed to have a JAR licence which easyJet TREs can sign. We have loads of French pilots working for us who all started with the 'old' licences, as indeed we all did. I do not expect this to be an issue for you. Best of luck.