There were some early COTTEENs in Lonan. One of my ancestors was Mary COTTEEN who married John GELLING in 1711 at Onchan. Her parents were Philip COTTEEN and Margaret SANTON. Phillip was buried in Feb 1725/6 in Lonan, died of Smallpox; Margaret a couple of years earlier. Philip's parents were Malony COTTEEN and Ann FARGHER, which is as far back as I've been able to go. Both Malony and Philip left wills, and there are a few other Cotteen wills as well from that period.
So the name COTTEEN goes back well into the 1600s in Lonan.