The thief is Scald!
Scald mentions there are 6 Jarls, yet 5 of their names are listed.
He says that Ivar was wounded, so he couldn't stand and had to sit down while telling his feat. Yet, Scald says Ivar sat down after his tale.
Ulf is mentioned in the given name of Jarls in the room, yet his feat is not listed in Scald's story.
Einar is not mentioned in the given name of Jarls, yet his feats were noted by Scald.
Scald's story says that Einar slammed both of his palms on the table and told his feats, but at the end, Einar removes his hand from Loki's shoulder. This completely contradicts what was previously mentioned by Scald's story.
Bjorns mentions he has a Level 4 Stronghold for his clan. However, the Strongholds today are unable to be upgraded past Level 3, yet.