From the manual, section 6.3.6. Undo, page 124: "Undo will only undo Paste and Erase operations; it will not undo randomizing notes in a Pattern or any of the other Shift functions. Another way to undo changes is to restore a pattern to its original state by holding 'Shift' and pressing Save. this will undo all the xchanges you made since loading the project."
I tried it, it works. Mess with your (previously-saved) pattern then press SHIFT-SAVE. Message on screen confirms: "Pattern reloaded". Random edits are gone, original saved pattern is back.
I did look for something in MCC which would let you limit the random range but haven't seen it. Anyone know if this is possible? I agree it would be good, and makes sense musically.