It would appear that archivists in the various national Irish repositories have wrestled with this question themselves over the years and compiled their own lists of what registers survived and where they resided versus what was believed irretrievably lost or possibly reconstructed in part from other sources. Well, now we genies can benefit from this insider knowledge too, as the RCBL and the National Archives of Ireland have collaborated and published this mighty tome online this month on the RCBL website - Table of Church of Ireland Registers throughout Ireland.
The PDF document runs to 98 pages and is a masterpiece of colour-coding that seeks to explain the status of the registers for what I presume to be the definitive list of every possible Church of Ireland parish in Ireland. Unfortunately the list is sorted alphabetically by parish name rather than say listed by county, so you really need to know where you are looking for in the first place - in that respect I would say it is very much a professional's aide memoire rather than a great finding aid for those less familiar with Irish geography. This is a bit of a shame as I could see how it could be turned into something so much more user friendly and helpful to both beginners and experts e.g. by displaying the colours on active maps. So, for example, whilst the parish you were initially interested in may not have any surviving registers, what about the surrounding ones? You can use the excellent Irish Times Placenames site to understand that aspect of ecclesiastical geography a bit better, but again you need to know what you are looking for.
Still, it's great to finally "know what isn't there" as it where and I can now see clearly that a trip to the RCBL in Dublin is required for my Co. Kildare research and I shouldn't have been surprised not to find my man on the IFHF site.