Couple points..

No pretense is made here of being an expert..
The "experts" are those that have been making boxes for generations...I listen to them and the results of their tuning, such as Beltrami.

There is NO SUCH THING as a "very dry tuned" accordeon.
Dry is dry,, it is unison.. anything else is a degree of wetness... be it 1 cent or 22 cents.

"defused" or diffused ?

Anthoer, and more important, point

So why ios it so darned important to be loud. Boxes by nature are loud. I go for tone.. TONE.
Tone is king. Need to be loud ? Get a mic.