Every possible plug in I can think of lately needs the possibility read and write the velocity of chords.

It would allow for note to note cresc. decresc. Plugins and chord accents, and If a visible note could be muted, and a different invisible voice could be played, then the possibilities are much more: Glissandos (cromatic, diatonic or micro-tonal), de/Crescendos (on 1 note), Harmonics, and all kind of articulations and ornaments.
(I think finale used to do this things exacly like that. When a trill was added and the "play ornaments" or something like that was pressed, an "invisible" new voice was actually written on the score with the notes of the trill.)

I don´t promise that I would do all that myself because I am just learning, and have a very very basic knowledge of javascript and non of Qt.
Thanks for all!
Love MuseScore.