As you are no doubt aware, there are many Keyboard Festivals in Europe, (Really big and popular over here) however they are dwarfed by the number of Accordion festivals.
Another point to note is that all European manufactures of keyboards have versions where the normal keyboard is replaced by Accordion keyboards; (And have done for decades) here is one http://www.wersi.net/html/mywersi-08.html# it is the second up from the bottom, and it is also why Midi modules from Europe integrate seamlessly with Midi Accordions.

Bill