I've had a go at the next bit myself:
> Ra·ngádatar* ara·mberad na sétu uili & ara·fácbad leo som na bú & in
n-ingin co cenn mblíadne.
[Thurneysen's footnote to Ra·ngádatar is "eher 'na·ngádatar'". 'Eher', as
far as I can tell, is German for "rather" or "more likely", so Thurneysen
appears to believe 'na·ngádatar' is what the word should be, but I don't see
much difference between the preverbs 'ro' and 'no'.]
'Ra·ngádatar' = 'ro·gádatar' (3 plural preterite of a verb, the deponent
preterite flexion of which is given in Thurneysen's grammar - unfortunately
it doesn't say what verb it's the deponent preterite flexion of. Most likely
option seems to be 'guidid' "prays, begs") + 3 sing infixed object pronoun
'ara·mberad' I thinking this 'ara n-' conjunction "in order that" + the past
subjunctive 3 singular of 'beirid' "carries" + 3 sing infixed object pronoun
'na sétu uili' - "all the treasures" (accusative)
'ara·fácbad' = ara n-' "in order that" + 3 singular past subjunctive of
'leo som' = 'le' + 3 plural object pronoun + emphasising particle
'na bú ocus in n-ingin' "the cows and the girl (accusative)
'co cenn mblíadne' "until the head (end) of a year"
"They begged him that he should take all the treasures and leave with them
the cows and the girl until the end of a a year."
"They begged him to take all the treasures and leave the cows and the girl
with them for a year."