This is a great idea Quetscher! I’d even be happy to meet with them as well, and have an open discussion with other Vibrandoneon/Eolina players.
1. An absolutely tight air chamber possibly made of plastic or lacquered wood.
Yes! Constructed in a way that is very easy and quick to remove, again and again, without wear and tear, so it can be dried quickly.
2. A moisture hole that is big enough to dry out the air chamber properly.
Moisture holes might not even be needed, if access to the air chamber is easy
3. The possibility to remove the back easier than to have to unscrew 19 screws (possibly some sort of quick release?).
4. Different mouthpieces for more flexibility and better possibilities to use different playing techniques.
5. A quick release for the grille to change the colour of the tone quickly.
Maybe even a hinging grille?
6. The possibility to assign the two sets of reeds (Blowing in and out) to different octaves (for example the reeds for blowing in sound an octave higher or lower than the reeds for blowing out).
I’d like to add:
7. Some sort of lever that allows the player to engage the second set of reeds instantaneously, so certain notes, or passages could be doubled an octave higher or lower as part of the performance. This would be fantastic for me.