What lore do you ignore?

[Iscah]

But without knowledge of "future history" you don't really have the choice to do anything differently.

There is no need to do things "differently" though – that implies that something is happening a second time. There is only one moment in all of spacetime where G'raha makes his choice, and he chooses it for his own reasons, not because some distant observer is already aware of what he chose to do.

Venat is no mastermind of fates; she simply considers the future that you describe to her and accepts to take her part in it. If anything, she is the one who has lost agency of her own future and can now only play the part that has been told to her.

...or perhaps she did struggle against her dictated fate, and she was able to act differently and split off a timeline that we will never see but the ancients are saved ultimately due to the warning we gave to Venat – but that can't happen without the original timeline still happening as well.