I actually do think that (eg) a couple where one's English and one's French often try to pick a name that "works" in both languages. There have been many such threads on here.
Eg eng and French couple might choose Lucie, Amelie
My Turkish friends, both Turkish but live in UK chose Leyla because it works in both countries.
So people do actively want their dc's name to be recognisable in all the places they currently live/are from/have links with.
If OP is in Ireland and doesn't intend to spend time living in England then I think that should have been stated in the OP. Due to the fact that the largest proportion of MNers by country obviously is England (due to the size of it's population relative to the other UK nations), it should have been stated that it was the opinions of people living in Ireland she was after, not the majority of posters. (If indeed that is the case).
In the event that the OP is after a name that "works" in Ireland and the rest of the UK, I personally don't think Fiadh is it. Irish names would be things like Shauna, Kerry, Alannah etc if you want them working easily in both places.
Or if you like the names simply because they have unexpected pronounciation (to English people) then I'd go for something more recognisable like Sinead, Niamh, Oonagh which more people have encountered. But on my original point, I know someone with Oonagh as a middle name (in England) who was highly embarrassed by it (yes, due to pisstakers and bullies of which your dc will encounter many) and she would never tell anyone her middle name and then it became a thing, they would not stop asking her. Etc