A suggestion: in the “Common” or “Notes and Rests” panel, provide a toggle for “Custom pitch” or “Custom intonation.”
Upon ticking the toggle with a note selected, the user would be provide with something similar to the “Custom scale” toggle in the “Common” panel.
As the user enters positive numbers the note is played back that many cents high; negative yields playback cents low.
I realize this can be accomplished with custom tonalities and custom accidentals, but one might have to create 96 divisions of the scale or more to achieve the needed potential adjustments.
The purpose here is to provide a means of playback that accounts for ensembles judiciously using principles of just intonation on individual chords to achieve the desired sonorous effect. (Bands are often told to play 3rds and 5ths of chords slightly out of (equal temperament) tune to make the chords more pure.) The composer can then experiment with the performance of individual notes and pass their desired intentions along to the players. (In that respect, possibly an additional toggle could be provided to actually print the change in cents over the note!)
Might it be correct to assume much of the programming for this already exists in Dorico through the custom tonality and custom accidentals interface? Could the new “Custom pitch” setting simply be a different way of interfacing with that programming?