Hi, It was me who told you the story of the the Cregeens originating from the Spanish Armada. I got the story from my father who I believe was a bit of a romantic. I have no proof however to its authenticity.
However, having studied my own geneoligy I can tell you that the name definately is most commonly found in the south of the island in the Parish of Rushen from 1750 onwards. The largest number of births, deaths and marriages are recorded in that parish. With a smaller number in the parishes of Arbory, Malew, Patrick and German.
Check out the website of the Church of Jesus Christ of Later-day Saints for birth, death and marriage records as well as census information.
Best regards, Phil in New Zealand