I’ve just submitted updates to Apple for both the Hohner MIDI Piano and Chromatic apps adding a new option to select between Bass/Major/Minor/7 or Counter-Bass/Bass/Major/Minor configurations on the bass side.
Here’s a couple of screenshots:
MIDI Piano version with the counter basses enabled
MIDI Chromatic in C-system and the counter basses enabled
Look for both as free updates on iTunes around September 10th.
Cheers and thanks!