No matter how you look at it, this conclusion was a bit too far-fetched.
The only evidence that Asgard could find were fleeting shadows in video footage and a series of recorded explosions.
Indeed, those records were rather blurry, and it was easy for one to misjudge the real speed of the culprit. However, these people were Martial Artists, not ones who could completely lose their sense of how "fast" something was.
The battle above and below the First Heavenly Layer should still be quite clear, shouldn't it?
Yet Jeanne remained silent, dragging her through the town's three-dimensional streets with what seemed like aimless wandering, but with anxious steps. She appeared to be confirming something at several locations.
