You may well be right... though I can't say I've ever seen it, or mention of it, in 19 C. Irish SONG books, FWIW. The attraction of the National Song Book as a possible source is that it would have been in the hands of teachers, in particular - and at a time when the sense of "Irishness" was being assiduously cultivated. I can quite see an enthusiastic National School teacher of the time setting about the adaptation!

Regards