Burns did "repair" many of the songs he collected. Indeed I think that was his most important contribution to Scottish song. I'm looking at a letter he sent to Alexander Cunningham from Dumfries, Autumn 1794, where he writes " I likewise gave him [Pietro Urbani] a simple old Scots song which I pickt up in this country, ... ".
My argument with the word 'instrument" is not that it is anachronistic but the whole phrase doesn't sound right for me. And Jack Campin who has collected a vast amount of Scottish material has never heard it either (his post above).
We could of course be wrong.