Krath, a made-up figure from children's stories, was well-known around the era of the Great Sith War. He was depicted as a wicked magician-god.
The cousins from Keto heard stories of Krath when they were young. The 'Krath' was the name that the two Force-sensitive family members gave to their dark-side cult after they matured and were drawn to the dark side of the Force. The name of their yacht Krath Enchanter was a clear nod to the character.