It looks like the shortcuts from cs6 won't work in pse 12 and they don't work in photoshop cs5 either, so adobe must have changed something.
Anyway, it's probably best to use the keyboard shortcuts from photoshop cs5, since pse 12 is mostly based on the photoshop cs5 code.
This the message one gets in photoshop cs5 when trying to load a keyboard shortcuts file saved out of photoshop cs6.
I thought so. I have my shortcuts pretty well as I want them, and used my CS5 at work to export a "final" set, but not having CS5 on any computer outside of work makes it difficult to change something if I need to. Thanks for trying that out!