A ऋषि Rishi records Itihas as a first person narrative of a story that is happening as they are recording it. This point bears contemplation.
A ऋषि Rishi is a द्रष्टु: Drashtu, because they have had the दर्शन Darshan, full perception of ब्रह्मन् Brhman, and are expressing this experience in story form.
A ऋषि Rishi is a Yogi who so crafts their life story that even "the gods" descend to play their parts to perfection in this human drama, not to mention the राक्षस Rakshasas, Humans, and all other beings!
A ऋषि Rishi thus sees beyond space-time limitations, and is thus considered a star being - hence the saying "our story is written in the stars".
There are many ऋषि Rishis in the original story each creating different sub-stories as part of the original story. The main ऋषि Rishi is of course the original author of the epic. A ऋषि Rishi seems omniscient because they are the ones of course who have written their story.
Usually everything goes to plan if the ऋषि Rishi continues their Yoga practices, but if they get shaken up (like seduced by damsels, or intoxicated, or angered, etc.), then the story could take an unpredictable turn.
The idea is to inspire people to become like a ऋषि Rishi, in charge of their own life story, but not to get so wrapped up in controlling it.
The truly wise ऋषि Rishi though, eventually drops control of their own life story and surrenders to the cosmic Leela, the grandest of all stories!