> En þó að í bresti nokkuð um þetta
> But even if (it is) in pieces (?) concerning this

'bresti' is the present subjunctive 3rd pers. sg. of the verb
'bresta', main meaning "to break". I don't remember meeting this
idiom before, but MM & HP's "if something goes wrong" looks rather
like Zoega (6) impers. "one lacks, falls short of; ef oss brestr á
borði "if we fall short, get the worst of it; þat mun aldri bresta,
at... "it will never fail that..."