Even if someone thought it was a good idea to offer a phonetic transcription, it's very difficult indeed because English isn't very phonetic in the first place. There's no agreed, consistent way of transcribing many of the sounds, particularly the vowels and diphthongs, of another language, especially as they may not correspond directly with the phonemes of the English. It can be done for the odd phrase or two, but to attempt to transcribe whole chunks of Irish into "phonetic" written English is almost certain to lead to a mangled and distorted result.

If a singer really wants to sing a song in a language they neither speak nor understand (not something I'd recommend), their best hope is to learn from a live or recorded version where they can hear how it should sound. And it's likely to work best in a song that was originally written in that language, rather than a translation.

Marje