I see no problem whatever with attempting to Anglicise, say Scots or Irish songs into the way you speak. It doesn't always work; on occasion the language is woven so intrinsically into the song that it becomes debased if you try to alter it, but it's certainly worth a try. If the song 'fits into your mouth comfortably' and if it works for you, it is quite likely it will work for an audience.
Traditional singers tend(ed) to sing as they spoke, taking their breaths with the punctuation - 'telling' the song, as they say in Irish.
One of the exercises we did in the Critics group was to first tell the story of the song in your own words, then speak the text as if you were telling the story. It can also help while working on a song, to move from singing to speech to resolve awkward passages. It quite often solved many of the textual problems of the song.
Making the song ring true for the singer was always the objective.
Jim Carroll