I'll take a crack at Englishing it:

You are the bright love of my heart, darling country of Conall
Lying as would green silk on the great sea
Oh, I love you always, early and slowly
And I praise you always, ancient Donegal

There is no county in Ireland nicer than you
There are no people in the world of better fame and repute
Nor is there in the country of Conall, in whatever region
Oh, you are the white flower of the land, ancient Donegal.

The tongue of our ancesters is spoken there still
As sweet, pleasant and delicious as song or music
Or angels in Heaven without stain or fault
Oh I love you forever, ancient Donegal.