Twould be a mistake to think that a piece attributed in 1650 to a source was really composed by the named person, not of course that it would make any difference to some people.
The Pibracht is full of way old stuff which may in some cases go back to the golden age of the Harper in Ireland. We easily forget that the Scoti were still very well connected in fairly recent times. Like 1700 for example. Sooo a tune can give every indication of being of Irish or Scots origin but turns out to be a hybrid from some other source! Ie neither.