For me its not far away at all that Blackrock and Blacksod can easily be mixed up.
Can you imagine the reference to the helipads in the FMS....BLARO and BLASO for example...
Dont know the CHC SOP for entering waypoints in the FMS but misstakes of putting wrong waypoint in the box can turn out very bad...like in the Cali accident.
If they had no Moving map either then its very easy to loose your situation awareness.
If that is the case and if they did not have NVD I would really question the operator to put the crews in such difficult situations with not enough resorces.