I don't know if it's of interest, but a few years ago I was studying Irish Gaelic [so I could understand what I sing] and I started a translation of this song into Irish. I only got as far as the first verse 'though:

Aon uair amhain Bhi beasai 's dlithe Gaeleacha Foliacht Gaelach i ngach graig Ag duiseacht ar maidin Ag duiseacht ar maidin.

I like to sing it at the end of the song.