as far as I can tell, it treats chords as individual notes… (midi is serial, so there is always an order, even if you think they are simultaneous) so it will use the last note for the transposition. if you play the ‘chords’ on live mode, it seems to almost be random which note it chooses (though in practice, if i use x3, i hear it using the top and bottom note pretty much alternating)
in practice its sounds ok, but its not quite as wanted.
it would be nice if we have a ‘bass note FX’ which filtered everything other than the lowest currently held note, this could then be used on a master transpose track to do as you wish. (albeit, you’d need another track to play the chord)
I guess you could try to flip this on its head, play only the bass note… and use the harmoniser + scale fx to generate the chord, but again not really the same thing.