I have just read R. A. Houston's book 'The Coroners of Northern Britain c. 1300-1700' He is Professor of Early Modern History at the University of St Andrews.
He makes it quite clear (page 3, for example) that the position is Coroner but he notes it is spelt in a variety of ways including Coronator and Crowner. Crowner? Yes; but it's not a two syllable 'regal' word as some like to think. It's a three syllable word with the middle syllable pronounced as row as in rowing so - K, row, ner. And that spelling is not surprising as it's all being written / printed before dictionaries set spelling in stone and with printers being of 'interesting' spelling ability...
So it's absolutely Gunn Coroner of Caithness...
Lots more to come, but that's after I re-read the book...