Unfortunately, if as on first hand, it is confirmed that the cowls were not latched and secured correctly, this is a classic Human Factors incident.
A very poor design by Airbus which has been notified to them on numerous occasions since entry into service of the V2500.
A modification to keep the cowls 'unfaired' until mechanically closed is also of poor design.
Even with safeguards like duplicate inspections to ensure correct latching, depending on time of day/weather conditions this could still be missed in the current era of limited engineering resources to carry out maintenance at most airlines, exasperated by the poor design.
All this could be remedied by either a better mechanical indication system or modification to latches of a similar design to other types such as on the RB211-535/524. Whether it's Airbus's or the Airlines reluctance to this due to costs is up for debate.