> og skal það þá fram koma.
> and that shall then be brought forward.

Emerge (become apparent)? Take place? Both these meanings which
Zoega has for 'koma fram' seem appropriate here. But I'm guessing
that it doesn't mean "be put into effect", since the verb would then
take a dative object: koma e-u fram. That's supposing that the dative
case would be kept when the verb is subordinated to impersonal
'skulu'; I think that's how it would work. Here -- bearing in mind
Eysteinn's warnings from last time I tried this trick ;) -- is an
example I found on the internet from Modern Icelandic.

Komi þá út brot, skal það hækkað upp ef það er meira en 1/2, ella skal
því sleppt.

If it comes out as a fraction, it should be rounded up if it's more
than 1/2; otherwise it should be let go / dropped.

Note: skal *það* hækkað ... skal *því* sleppt.

LN