Different Z height could change the resonance characteristic, i wonder if we could do sample multiple frequency swipe across different Z heights and selectively apply it on X axis, Y axes or both. Missing values are interpolated.
I don’t know too much about the active damping of klipper, but I presume that only the amplitude might change, not the “characteristic”. The native frequency should be similar or equal, no matter, where do you place the Z-Axis. This is also true for all other axis, depending on the frame configuration.
Another spect is the frame configuration. A typical bed-slinger should have no problem with X-Axis test at different Z-Heights since the inerta of a square frame should not change too much. My voron is like a rock, I checked the results at two heights 100mm and 200m for a 350^3 frame and there was no visible difference. The Y-Test should be independant for Z-Axis for a bed slinger, too and Cubes should be ridgid at all Z-Heights. So only for T-Shaped Z/X-axis configurations (gallows-type) this could be considered to be important.
Does amplitude matters? My gut feeling says: it doesn’t! Klipper says: there is no value to enter beside the native frequency (=it doesn’t) but I have no mathematical proof for it.