Sorry, that's It's not possible with Overpass API today, i.e. you need to resort to some way but with a bit of post-processing like filtering you can get the results in JOSM or some Excel formula, etc.
If you like you could also raise a ticket on Github and propose such a feature.
Here's a small few minutes.
The Overpass QL query returning all below returns relevant nodes/way/rel with all having a name, name:en and name:ga tag in CSV output format (tab separator character) for easy consumption in Excel/OpenOffice/... character).
To get the data, just click on the following overpass turbo link: http://overpass-turbo.eu/s/9FN and then hit "Export" -> "raw data directly from Overpass API". This should automatically open LibreOffice or Excel, depending on your local machine. When importing the CSV file, make sure to specify "tab" as separator character.
There are only 11120 rows returned by the query, about 300 of them match your search criterion.
Just add a formula to all rows to compare different names and you're probably all set.
[timeout:1800]
[bbox:51.08282186160976,-12.8759765625,55.986091533808384,-1.86767578125]
[out:csv(::id, ::type, name, "name:en", "name:ga")];
( node[name]["name:en"]["name:ga"];
way[name]["name:en"]["name:ga"];
rel[name]["name:en"]["name:ga"];
);
out;
Result:
Overpass QL result in CSV format, as returned by Overpass API:
@id @type name name:en name:ga
661291 node Sutton Sutton Cill Fhionntain
661448 node Killester Killester Cill Easra
661999 node Glenageary Glenageary Gleann na Caorach
662088 node Booterstown Booterstown Baile an Bhóthair
664528 node Shankill Shankill Seanchill
665844 node Cowper Cowper Cúipéar
666663 node Milltown Milltown Baile An Mhuilinn
12646992 node Carrickmines Carrickmines Carraig Mhaighin
12647002 node Carrickmines Carrickmines Carraig Mhaighin
12647038 node Cherrywood Cherrywood Coill na Silíní
19223931 node Windy Arbour Windy Arbour Na Glasáin
26608599 node Cork Airport Cork Airport Aerfort Chorcaí
26608601 node Shannon Airport Shannon Airport Aerfort na Sionainne
28650950 node Cooanmore Point Cooanmore Point Gob an Chuain Mhóir
28652693 node Killaspug Point Killaspug Point Rinn Chill Easpaig
[...]