While the procedure of gaining experience as an SO operating the FE's panel is traditional and highly respected in the US, it's not known in Europe. So, the essential answer to your question is that employers in Europe are unlikely to give you much credit for this time unless they currently operate a scheme for retraining their own FEs as pilots, and are thus familiar with the benefits of FE time (in Europe, the Flight Engineer is a career trade in itself, but many of the younger ones are now retraining as pilots).
As for converting your licence to the necessary JAA one, which presume you will need to do, I would strongly recommend you talk personally to Flight Crew Licencing at the CAA (or their equivalent in your chosen country) and get a ruling on what your SO/FE time is worth.
Scroggs Virgin/Wannabes Moderator
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