> the longest/most complete reports
Spot on! You can find 'gerst' hiding in Zoega under the guise of:
"gørr, adv. compar., gørst, adv. superl. more, most fully." Like the
positive of this adjective, the vowel can be spelt in various ways
(görr/görst, gjörr/gjörst, gørr/gørst, gerr/gerst).
Ok hefir Karlsefni gerst sagt allra manna atburði um farar þessar
allar er nú er nokkuð orði á komið.
"And Karlsenfi has told most fully of all men the details of all these
voyages which have now been to some extent recounted."