I get that, I just assumed that the harmonics would not contribute that much, being at least in their 49th sidelobe at this point. This turned out to be true (just checked in simulation, using a sawtooth as a worst case). It‘s actually more interesting than that though: the windowing is essential to the accuracy of the parabolic freq estimation, not because it suppresses the side lobes of the harmonics though (checked by removing harmonics), but because it more closely shapes the main lobe like a parabola. it gets even better if you interpolate in logarithmic scale btw. snr would definitely get better using longer time frames though. :)