None of our universes have been destroyed yet. Aurora-chan confirmed that they will not be as long as we continue to participate in missions.

[Which in its own right is concerning, honestly. What happens when you don't comply? How immediately does it happen? Or was that answer its own sort of test?]

To my understanding, what Echo-san intends to do is not save universes directly, but preserve the integrity of the multiverse by culling some of the individual universes within it. What we're here to do is convince Echo-san to spare ours from destruction.