Another nonsensical one I have seen in the US is fir na tine which literally translates as men of fire, in that the men are composed of or made of/from fire. I have seen fir na tine used in the US, but I've never seen it in Ireland or Scotland, but fir dóiteáin is very common.
Fireman = fear doiteáin
Firemen = fir dóiteáin
Firefighters = comhraiceoir dóiteáin
No "fir na tine".
I may have mentioned this before, but you have to be very careful with these translations, back in the early days of a bagpipe forum I frequesnt, someone asked for a translation for "Men of the thin blue line" for a "Celtic" US police pipe band, and was presented with a mish mash of Scots Gaelic and Irish Gaeilge that translated as "I copulate with thin blue men". No joke, I wonder if it's on a drum head somewhere?