I converted the frost giants using my 1e and 4e versions for inspiration. It's a shame that they didn't convert them from the 4e versions in this book. My versions of the Jarl and his wife gave him a feat, higher strength, higher hit points, and legendary actions. His wife had a lair action. They seemed more fun than just ripping off cloud giant stats but in fairness that's pretty much what 1e did, I suppose.