[Stephen]

Googling, I can see some theoretical similarities with a 2001 German Seydel patent for a chromatic button melodica / wind instrument.
The patent can be viewed at the office patent:
https://register.dpma.de/DPMAregister/pat/PatSchrifteneinsicht?docId=DE10010516A1

Figure 1 in this patent shows the reeds are in a horizontal position, same way most melodica reed plates and reeds are.