The standard crayfish is always going to wreak havoc on a planted tank. Anyone who disagrees I'd like them to post an actual picture of the tank to prove it.
IMO, the "barrier" is a waste of time & money. Unless you cut off it's legs, a crayfish should easily be able to scale the wall.
The crayfish I've owned have stripped several branches that was completely covered in moss, completely BARE.
Even Amano shrimps will eat plants & fissidens if they can't find enough food.
Unless you have no life & can feed every 12 hours, crayfish will always be on the hunt for decaying matter & will gladly devour plants if it can get a hold of some.