There is no such thing as a foolproof system, because fools are too ingenious.
Wemher Von Braun
Most aircraft/engine types have had the rare occurrence of an unlatch cowling departing the airplane. You can make the system fool resistant, but it is really, really hard to make it foolproof (see above quote). Problem is, the V2500 loosing engine cowls is not particularly rare.
It's clear there is something unique about the V2500 installation that is resulting in the relatively high rate of cowls departing the aircraft. It's also clear that the steps taken so far have not addressed the fundamental problem.
The FAA considers 'parts departing airplane' to be inherently unsafe (and I'm sure EASA has a similar policy).
BTW, who provides the V2500 engine nacelle (or does Airbus make it in-house)?