I Panned root note to Left, then following semitones to the Right - and in the Renoise oscilloscope one can see the Curves/Figures.
I attempted to find the nearest fine-tuning match for a given semitone - so, that relating to root note C, it creates a stable curve in the oscilloscope. There is a bit of jittering because, I guess, of the limits for fine-tuning resolution available - 1/128.
Try playing C + E or C +G.
C Major sounds good imho.
If you want to play with other root note - change the Instrument Global Pitch semitones, e.g. C → D is 2 semitones up, etc etc.
I think the curves are rotating, because there is some kind of frequency or phase drift, and perhaps because I can not really fine fine tune, the frequencies are still slightly off the perfect interval.
You can add some distortion and\or bit-crush on the efx or in the mod efx - looks interesting too. Or redo it with different base signal shapes.
You only have to do one octave, if it’s is 12 step scale, and then just copy paste the rest of octaves.