I haven't thought this through (which may become very obvious), but I wondered if anyone had tried making an English concertina with only one reed per note, and using a "bridge rectifier" approach to always direct the air through the reed in the right direction? The bridge rectifier uses 4 diodes (or leathers, in concertina parlance):
As you can see, it doesn't matter which polarity the power source is (positive or negative, suck or blow), the diodes (leathers) steer the current through the load (reed) in the same direction. It does require 4 leathers rather than 2, but gets away with one reed rather than 2. That would seem very attractive on a 56 key English for instance, offering half the number of reeds, and no tonal, tuning or volume balance issues between reeds. But is it possible to come up with a physical structure that would accommodate all that? I reckon it would have to put you in line for a Nobel Peace Prize.
Here's a rough analog of the EC, with two leathers sending the flow in the right direction through two reeds:
|------>|-------/\/\/\/\----------|
--------| |--------
|-----/\/\/\/\------|<------------|
Terry