The liner notes and the lyrics I can find on Google include some Irish Gaelic for part of the song, and while I don't speak the language I can tell what part of the song those lyrics appear in. Those lyrics are as follows:
Amharc, mn ag obair l ‘s mall san och’,
Ceolann siad ar laetha geal, a bh,
Bealach fada annon ‘s anall a choch’.
However, bookending this section is a repeated set of lyrics that I cannot find anywhere except in a sort of hacky phonetic transcription. I have always assumed those lyrics are Irish Gaelic as well, but if that is the case, why has no one transcribed them properly anywhere? Can any Irish Gaelic speakers here tell whether the multiple-Enya-voice-Borg is singing in that language at the beginning and end of the song?
Furthermore, if it is not Irish Gaelic there, what language is it? Is it even a real language or is it some of the random syllables that I think might also be in some of Enya's other songs? As I sing the phonetic transcription to myself (link also includes an odd theory about the song), I oddly find myself hearing phonemes + melodies that seem to belong in an indigenous American song, given my scant familiarity with languages like Navajo, Lakota, and respective musical structures. But I don't know which is more absurd— my forming that association, or the prospect of Enya trying to sing in Navajo.
Who can help unravel this mystery?