Sort of OT but when I tightened my Keo cleats pretty firmly they just cracked. Now I snug them but don't crank them.

I think the sandpaper/adhesive idea would work well.

Also it seems that it's an isolated problem. I don't know what the cleat interface looks like but the SPD-R cleats (metal cleats) had so little surface area contacting the shoe that you normally had more force holding the cleat in the pedal than the cleat on the shoe. It was way too easy to move the cleat instead of clipping out. On that cleat I really tightened the heck out of the cleat bolts.