I may be wrong, but I had gotten the impression that some of the oldest/best-known/favoriate Irish traditional songs have "trditional" lyrics in both Irish and English ~ that is, an English translation of a given song may have been created so long ago, and been "folk-processed" by a bilingual community for so long, that the English-language version is very nearly as well-established in tradition as is the original Irish.

Taking a Gaelic lyric without an established translation or "variant," and coming up with an English version on one's own, would certainly present the kinds of problem/dangers that An Buachaill Caol Dubh alluded to an hour or so ago. Certainly not a job for some who does not understand the original language, that's for sure.