I am trying to think of examples but there are supposedly surnames where the version used in dialect speech was rather different - "Colcheragh" for Qualtrough and "Codhere" for Watterson (McWatter) where do these fit in?

Another point is that women's names are regularly recorded as "Jony Quine alias Kelly" or just Jony Quine before 1700, where Quine was her maiden name. Presumably in Manx she would have been Innee Quine regardless of marital status. After c1700 the usage in the records flips over and she would usually be "Jony Kelly alias Quine".