Thanks for the useful information about Austrian traditional music and the Hotel Speilmann. You may be interested to know that, when I was at the Heidenheim Festival in Southern Germany, there was a team of young Austrian folk dancers accompanied by a musician who played a massive melodeon-cum-accordion. It had four rows of buttons and and, at the bass end, eight soundholes looking very much like trumpets to carry the sound of the massively deep chords. Other musicians play the squeezebox, but this magnificent thing actually grunted!
I've got digital pics of the melodeon-accordion if you want to pm me.