If you have not yet found him, check out Patrick O'Flaherty. He has a website (can't make a blicky from work but will post address). He grew up in the Gaeltacht in Connemara and on the Aran Islands and so is a native speaker of Irish Gaelic, and one of rather few writing songs in the language. He is currently is the DC area. He sings in Irish Gaelic (and English) and plays accordion and also was described in "Irish Voice" as "possibly the best mandolin player on the planet." He can often be heard at Pat Troy's Ireland's Own.