Arco To Pizz Playback Is Not Correct

Some observations, if I may.

I’m not sure I understand what “arco+pizz” means. Is it about the attack of the note? Is it about the length of playback? Is it only in Muse sounds? How could we hear an arco start of a note if there is also a pizz. I would think that the pizz would over take the arco.
In any event those of us using Basic sounds aren’t really hearing the same thing the OP does.
Here’s what I hear:
Muse sounds, cello staff, cello solo-A very clean pizz.
Muse sounds, cello staff, cello section-a slightly more muted pizz.

It sounds like the font is trying to emulate several cellos playing pizz not quite all together. It seems to me that a section would not sound like a solo player.

This what I hear on my system and on the video.