[kazinator]

"Almost Tonnetz" fail:

https://en.wikipedia.org/wiki/Stradella_bass_system

Accordion buttons have a row of roots with major thirds off on a diagonal, but in a shifted way that you don't have minor thirds on the opposite diagonal. E.g. there is no CEG triangle.

If the layout did that, you could hit minor and major triads chords by pressing triangles on the first two rows.

[pasteldream]

Why did they make it like that? I assume accordion makers were aware of the convenience of the harmonic table layout, and had good reasons for choosing something else.