I agree that Hyland could derive from some kind of Scandinavian or Viking name, but the letter 'y' would probably be one or two other letters in Norse, Danish or Swedish - and the 'h' might not have existed at all, but be added on by later English speakers.
So you might have started with something like: Aeland, Ajland (where 'j' sounds like Englsih 'y' or 'i')or perhaps Eiland, or even Oiland or perhaps Åland (= Engl. OH-land)
Another thought about Yealand. Since you say it is a place name in Cumbria, which is in the far north of England, it likely is from some Scandinavian word. I don't know "jalant", but the part of Denmark that we call "Jutland" in English is called "Jylland" in Danish (= Y-EYE-land), so perhaps HYLAND could have evolved from that.
When trying to spell Scandinavian words, try holding down the ALT key and key in the following numbers:
ALT 0197 = Å ALT 0229 = å ALT 0198 = Æ ALT 0230 = æ ALT 0216 = Ø ALT 0248 = ø ALT 0156 = œ ALT 0140 = Œ