"real" accordion support

There are some differences in common piano and accordion (and variants, like Russian Bajan) notation because of "Stradella" left hand layout, that have chords instead of notes
1) Bass notes/chords are very loud, so played in staccato by default (when you need to hold, as you do by default on other keyboard instrument, you place a tenuto sign)
2) Bass chords are written one octave higher than real sound(to differ with "free bass buttons"), sometimes that make MuseScore to mute right hand sounds
3) Individual bass notes are actually octave three-note chords
Yeah, I know, that I could fix it with hidden notes and symbols, but tired of doing it every time
and 4) Left hand and right hand are separate parts of mechanism, but I couldn't pan them differently to make a stereo effect that could be heard when playing accordion, they are counted as single track