These are good comments and questions and I thank you for asking them.

You are perhaps correct to say that we only need know parental relationships and I think reality is something like that. Much of the philosophy of mind concerns itself with exactly this. For example, see this essay by the philosopher Daniel Dennett: https://folk.idi.ntnu.no/gamback/teaching/TDT4138/dennett84.pdf.

In fact, if you think about it, perhaps we only need to know the rules and not concern ourselves with the facts. For example, maybe we only need to maintain the following rule, which captures the parent/child relationship, {IF 𝑥 is the parent of 𝑦 THEN 𝑦 is the child of 𝑥 AND VICE VERSA}. This way when we get the information that, say, Satyavati is the parent of Vyasa, we immediately know Vyasa is the child of Satyavati. (Add in a rule like { IF 𝑥 is female THEN 𝑥 is the mother of 𝑦 } and you can infer more.) But how many such rules exist? Which are the relevant ones? Is “third cousin, twice removed” a relevant rule? (I don’t know but I’m not placing any bets either.)

But how does all this coexist with Vyasa’s request for “complete understanding”? We must pay fidelity to that request given the context in which it was made—he made it so he could eat, sleep, etc. So, according to the rules, if we suppose, as you suggest, that if “Ganesha did not understand first hand…” then he must not write anything.

Clearly human cognition doesn’t work as described in my post because if it did then, as Dennett points out in the above essay, we wouldn’t be able to get out of bed and make ourselves breakfast. But humans haven’t made any committments towards “complete understanding” either.