". Has there been any observational evidence of rock layers folding without cracking once hardened?""

Golly Pete... that is, by definition, not possible for humans, as we only live for a hundred years or so. (and not only that, but 'hardened' is a relative term for some types of sediment. Just imagine rocks mixed with clay... you can bend a layer s-l-o-w-l-y AS it hardens)
You keep returning to that theme about everything related to 'very old earth' and evolution. It is a nice convenient argument to deny or cast suspicion on processes that **science** shows us took a long time, but you can't disprove lots of scientific evidence by just demanding that it MUST happen as we watch. What do you want...video of evolution and geologic processes? (You actually can have that when large earthquakes happen and one piece of earth rises several feel above another)
   You are using very awkward and artificial criteria for your criticism. I could use the same type of argument about other things in everyday life, and you'd immediately see why it was not fair... but you NEED that demand for 'observational evidence' in real time to support your primary premise of 'creation' being only a few thousand years ago.