Volume unbalances with strings' bow techniques

[julenComposer]

Issue type

Muse Sounds bug

Bug description

Dear devs, I'm afraid that the balancing of solo bow instruments from the piano dynamic and lower is still to be fine tuned. Depending on the bow technique ("sul pont." and "sul tasto") the difference in volume between solo violin 1, 2 and viola change really dramatically, to the point that some of them can be barely heard. You can work around this issue by just using invisible mezzoforte dynamics for viola or violin 1 and then insert dynamic symbols in normal staff texts when a piano or pianissimo is needed, but I think it's not really a solution.

Steps to reproduce

1. Create file with all solo strings (solo violins 1, 2, solo viola and solo cello)
2. Write three measures of phrases/tutti chords with all of them, with only a piano dynamic at the beginning
3. To all of the four insturments, for the first measure use the "normal" technique, then for the second measure apply the "sul pont." technique and finally for the third measure use the "sul tasto" one
4. Playback the score
5. Compare the volumes

Screenshots/Screen recordings

Here you have a simple example of this issue.

MuseScore Version

4.2.1-240230937, revision: github-musescore-musescore-d757433

Regression

No.

Operating system

Windows 11

Additional context

No response

[bkunda]

@zacjansheski pls investigate

[zacjansheski]

You can see in the mixer violin 1 and viola almost entirely disappear on the sul pont. and sul tasto chords

https://github.com/musescore/MuseScore/assets/69917893/cc5e2f63-546a-4ca6-b91c-9f9fd4631227