George Buchanan was the really important Scottish writer in Latin. The Scottish History Society reprinted a collection of his Latin political verse, which is as forceful as anything Dunbar or Lyndsay produced. Far from deriving from the court of Mary Queen of Scots, he was a ferocious anti-Catholic satirist. Latin was his appropriate medium because he tore into every Catholic ruler in Europe (and spent some time in jail in Portugal for it) - he wanted to be understood by the educated class everywhere in the continent.

Buchanan mostly used classical Latin verse forms. There are some epigrams and shorter poems that might fit Scottish song tunes.

The editors of the SHS edition think Buchanan's native language was probably Gaelic, but they don't have solid evidence for that.

A somewhat earlier Scots Latinist was Gavin Douglas, but his major work is a translation of the Aeneid into Scots. Not sure if he wrote much in Latin.