Translation:Irish dictionaries are written in Ireland normally.
There may be some dictionaries out there that use the word Gaelic in the title, but most of the Irish-English dictionaries available in Ireland say Irish, rather than Gaelic.
I'd be inclined to say that it would be a little bit misleading to accept "Gaelic dictionaries", because that's not really the phrase that is used in Ireland, even if it might not be technically incorrect.
But Gaeilge can also mean Gaelic as a whole (Irish dialects, Scottish and Manx), and each of them seperately (although, then, it would rather be put more precisely as Gaeilge na hAlban or Gaeilge Mhanann). So, I believe, it could be translated as Gaelic dictionaries, Goidelic dictionaries or even (on some rare occasions) Manx dictionaries…
However, I do not think they would be appropriate translations to be accepted by Duolingo because still Gaeilge, without additional context and information, is understood as Gaelic dialects and official standard of Ireland a.k.a. Irish.