... perhaps I am missing something here, but I would think that people using 'one finger chord mode' are only looking to play the most basic chords they can, perhaps due to the lack of knowledge of how to construct more complicated chords ... that being said, I would expect a MOTL or especially a TOTL keyboard to recognize whatever I am playing in the left hand below the 'split' location and play the appropriate chord - REGARDLESS of whether I am playing in 'one finger', 'multi-finger', or 'five fingers and two toes' mode ...
I do realize, however, that there are going to be some limitations ...
I guess people might use 'one finger' (I had somebody use that on me while driving the other day - I'm sure it wasn't anything 'minor' he was thinking about ) to easily play a Major chord just by playing the root, even though they may be constructing chords using 4 or 5 fingers like Ted ...