Firstly, FaceCradle is designed so a relatively light load is applied to it when in use. This does not mean that it will break. To the contrary, about 80% of your body weight is transferred to the base of the seat, not to the FaceCradle. So depending on the angle you lean forward in deep sleep mode (the further forward the more load) no more than 20% of your body weight is ever applied to the FaceCradle.
We do it this way, so the pressure on your head and face does not become uncomfortable.
For example, a 100kg person applies less than 20kg of weight to the upper and lower pillows combined. This weight is held over your head, upper body and chest and the spread is transferred through the internal reinforced frame to the metal hinges and then to the straps which are anchored to your seat.