Daybit
Why else do you think Anastasia was chosen for the raid on Chaldea?
It was to preserve CHALDEAS within the ice.
The renaissance genius Da Vinci might have been able to realize the truth during the raid.
In which case, even if destroying CHALDEAS would be out of her reach, she might've been able to cause some kind of malfunction.
That in turn, could have served to delay the plan.
After all, Chaldea still had the option remaining to Rayshift into CHALDEAS at that time.
That was taken into account by CHALDEAS, which is why it was made to appear as if it had ceased functioning by being covered in ice.
And you actually did give up on CHALDEAS back then, escaping from the South Pole in the Shadow Border.
Thus distancing yourself from the point where the real culprit was located.