Just one very minor comment:

> Hefir þú þær sakir óbætt við þá sonu hans.

> You have the acts that cannot be atoned for by money with
> his sons.

> You have not attoned with those sons on their behalf for
> him.

> You have not-atoned(paid for, adj) those offences (sök)
> with them, his (ie Bolli´s) sons.

I'd treat the past participle as a pure adjective and make
it simply 'You have those unatoned offences against his