iPad Air keys freezes Whenever I activate "reduce transparency" in the accessibility menu, the onscreen keyboard keys stop moving. Normally they make an effect that seems as if they were actually pressed down.

Does anyone else have that issue?
My iPad 4, running iOS 8.1.3 flashes each keystroke by inverting the keycap background colour from white to grey.  This behaviour doesn't change as I toggle: 

Settings --> General --> Accessibility --> Increase Contrast --> Reduce Transparency

on and off.  So you might have some corruption in your iOS instance.  I recommend backing up and restoring.