Interesting one alright. I suspect it was never a song - and would be sceptical of the "Translated from the Irish" claim. To me, the whole poetic sensibility of the piece is mainstream English of the time. Given its date (1828), it seems to anticipate the Spirit of the NaTION genre of Davis and his contemporaries in The Nation. The pseudonym Hibernicus, of course, means "An Irishman" and seems to have been used a lot in the 19th C.

Regards