are you sure it's non trivial? they posted a 2d image of what it looks like. a fairly simple model of the users wrist and mouse position doesn't seem crazy hard but the devil is in the details
Naturally it depends on how well Cloudflare built this implementation. In the abstract, though, a sufficiently accurate prediction system should expect to recover the causal structure of the phenomenon it is attempting to predict, and thus an imitator hoping to defeat the predictor should expect to contain the same causal structure (i.e. physical simulation of a human hand to arbitrary level of detail).