Can you post details of the book, please - or arrange to get a PDF of the page to me? Your brave effort at transcription has some ambiguities.
A first run at translation would be:
A truly beautiful and truly Irish air goes with this song; but unfortunately - the old words are lost. It has been made into a lovesong by some poet who put English words to it.
The second Irish quote says:
The translation which follows was made by the editor.