Charlotte is definitely doing those things on purpose. The question is whether she is doing it for fun and making them look like accidents, or is she trying to drive a wedge between Sylvia and Teppei so she can step in? Since the first two times occurred before she knew that Slyvia and Teppei were betrothed, it is far more likely the former than the latter.

Charlotte is calculating, but excellent at playing innocent. They spun around a couple of times to land on the desk last episode...where she immediately wrapped her legs around him. Here, she landed on top of him, and rather than get off, she proceded to bounce and incite Sylvia further. She's very skilled at playing coy.