I don't think Carolan's authorship is disputed for this one, it is for many other tunes attributed but not for the 'concerto'.
It was composed for Elisabeth Keating, later Mrs Power/Poer and was published as such (mrs Power of Coorheen) as far back as the 1780s. Supposedly inspired by Correlli's music, although the famous (debunked) anecdote was about a contest between Carolan and Germiniani.
I have seen many harpers play it without difficulty, on modern-ish Irish instruments as well as the wirestrung harp. It really comes alive on the wirestrung in the hands of a good player. As Jack says, it's an easy to remember piece, it's not one I would play but I can when it comes up.