I understand that the question is rather difficult. I don't know if it is a new feature for the Genos or if it already exists in the Tyros5.
In fact, the guitar part, on CH#12 uses a D-Folk Guitar Megavoice, and the channel#13 uses a Mandolin Megavoice.
For the megavoices, I am aware of the levels of velocity to select a specific sound of guitar for example or to select a typical guitar effect as a hammer-on or a slide effect.
We just need how work the notes C,F,G,A,B, that is what is the role of each note for the resulting chord (what note is the 3rd, the 5th, ...) ?
I just assume that the C key is the bass note of the chord.