The bound in Section 3 is correct and, as far as I can establish, new. The evaluation that follows it does not test the thing the bound is about.
What works
The derivation is clean and the constant is not hidden. Where similar papers bury the dependence on window length in an appendix, this one puts it in the statement, which makes the claim falsifiable.
What does not
Two of the three traces contain a documented regime change. The third does not, and including it inflates the average improvement without adding evidence. Removing it would strengthen the paper.
What would change my mind
A synthetic trace with a controllable drift rate. That is a day of work and it would turn a plausible result into a demonstrated one.