As a surname, Rawnie turns up very rarely in Lanarkshire, Scotland (http://search.ancestry.com/cgi-b…).
As a first name, Rawnie is indeed English Romani, from the Romani rani for ‘lady’ (Message: “Re: Romani names”); it corresponds e.g. to Hungarian Romani Aranya (https://books.google.com.au/book…)
MacKenzie is an Anglicisation (with garbled yogh) of MacCoinnich = Son of Kenneth: Mackenzie (surname) – Wikipedia.