Flying through CBs at high altitude, near the "coffin corner" at night is simply crazy. That's why we have weather radar.
For the umpteenth time, there is no evidence the crew flew through a Cb. In fact, based on the last BEA report, the crew knew very well what was coming,weather-wise as they turned to avoid and briefed the cabin crew.
Had they then encountered mod or severe turb in the top of a Cb, I'm sure the BEA would have mentioned it.