For Kerry, long-distance travel had nothing to do with the distance in reality; what mattered was the structure of the Behind-the-Scenes Dimension. In fact, when she "leapt", she was actually progressing in the Behind-the-Scenes Dimension, where every point in space had a corresponding point in reality. However, the distances between the points were different. So sometimes, a few meters in the Behind-the-Scenes Dimension corresponded to thousands of kilometers in reality. Furthermore, her speed in the Behind-the-scenes Dimension was completely different from her speed in reality.
In the past, she hadn't been aware of this and had simply acted on instinct; as a result, the distance she could leap was limited. But now, with precise calculations, she could travel between far-off locations at will.