The key to St. Brigid's Ale-Feast, obviously, is in those three verses which Sean Ó'Faolain decided to omit. Most particularly, it is in those two words in the seventh and final verse:
císaige; and flaith.

To complicate matters further yet for a translator:
"flaith" is two words in one, with two entirely different meanings.
One meaning of "flaith" is beer or ale.
The other is landlord, chieftain, feudal baron.
It is actually indicated which of the two meanings is intended, by that key word "císaige," which means a vassal who pays tribute/rent.

So this feudal metaphor is Brigid's celebration of the sovereignty of her heavenly Lord and of the privilege of being His vassal. And the whole point of uniting Heaven and Earth at an ale-feast where she dwells, is not to get everybody intoxicated, but to rejoice in a harvest of virtues.