I wonder how well adaptive timbre could work? Could we have timbres that coincide perfectly for fifths, thirds, sevenths(ish) without having to do adaptive tuning? Just, you know, FFTing the input signal, picking out the odd-numbered overtones, raising the third harmonic by 2c, the fifth by 14, the seventh by something like 30c, etc. (With a synthesized signal it would be easier, of course, since no adjustment of input after FFTing it is needed)

Would different tones of a chord need them differently adjusted? Is there a way to uniformly adjust harmonics for all tones so that 12tet basically would have the benefits of JI when it comes to harmonics coinciding? Or is this a pipe dream? Would the timbres sound way too weird?

Could there be a non-equal adjustment that wouldn't be adaptive, such that e.g. Dmaj and Gmaj, despite having the identical 1:2^(4/12):2^(7/12) frequency patterns have different enough out-of-tune harmonics to, despite both sounding good and major still sounding interestingly distinct, a bit like a timbral equivalent to the non-equal temperaments that were in vogue before 12tet?