Interesting.
My understanding is that the JAR rules actually aren't very harmonised at all in this area, and that the UK allows a more-or-less unique degree of freedom for non-IR and indeed non-IMC pilots to fly under IFR.
If the IAA has chosen to model its rules on those of the UK then that's jolly helpful of them. As you suggest, giving them a call is probably a good idea.
Did you do your Waterford night trip in the end?