as I said a few days ago, I prepared a first example on how to use the Spontini editor to create very complex scores for piano, which combine cross-staff and polyphony.
Other examples will follow, more and more complex.
The bars are taken from a prelude of Debussy ("Danseuses de Delphes"):https://github.com/paolo-prete/Spontini/blob/master/examples/polyphonic-tabular.md
As can be seen, the procedure for obtaining this result consists
1) In the automatically formatted and tabular insertion of cross-staff notes
2) In adding polyphonic voices, using the same cross-staff functions provided by the editor
3) In the final ** fast ** tuning with the mouse (without therefore the trial-and-error process) of the various grobs, which obviously cannot be positioned automatically by Lilypond given the graphic complexity of these scores.
It is pure utopia / dogmatism to believe that Lilypond can solve the positioning of the grobs on this type of score through algorithms.
And these scores are MANY and MANY.
This is not a Lilypond problem: it is simply impossible even for the most advanced software on earth. In fact, this example also shows how great is what is done automatically and natively by Lilypond (because the collision avoidance mechanism works great).
In any case, I believe that without the help of these tabular functions, without the *many* workarounds added in the easy-cross-staff functions and without the graphic tuning with the mouse (jsTweak), writing this type of score takes such a long time that the task is practically impossible.