Jumping ahead and making a stab at translating the next verse:
> 24. *Trî haidche garbo a nGlenn Gerg
> do bî Tadg re glór an ˙fir,
> gan tionnabhradh, trûagh an feidhm,
> do bâdhus fêin ann faris.
Three nights it was in Glen Gerg
Tadg was (with the voice/noise of the man??),
without sleeping, not that that did any good,
I was there myself along with him.
I have no idea what the sense of it all is, though.
[Tadg was there making manly noises about protecting cattle (which still
got stolen in the end) - wild guess]