Sounds cool! Not every feature needs to be used in all cases 
That said, if I understood it right then the square Trill actually supports multitouch, it just cannot say which y positions belong to which x positions, just just get a list of both. So one could e.g. play chords on a horizontal “string” (which string could be determined e.g. by the lowest or highest y position). Building a big surface with the squares would need quite many of those, but your x/y bars might be a good idea to get more out of just one square…