PEI 3721
CP, #1558
1. ‘They were in a CB’’. There is no evidence that the aircraft was in a CB; the crew had seen and planned / turned to deviate around weather.
Without the release of the full CVR transcript, there is no way of knowing what they saw, or didn't see painted on their radar. We do know what the Lufthansa, Iberia, and AF459 crews saw on their radars that night because they have told the BEA.
As for the Cb, the satellite imagery of 02h07 as analyzed by Meteo France (included in the first interim BEA report) indicates at 02h10 off their starboard wing there was a rather cold cloud top:
On constate qu’à 2 h 07 les températures les plus froides sont de l’ordre de -75 °C à -80 °C, alors que la tropopause se situe entre les FL500 et FL520, avec une température voisine de - 80°C : certains des cumulonimbus de l’amas ont atteint l’altitude de la tropopause et leur stade de maturité, mais l’imagerie ne révèle aucun développement vertical exceptionnel du point de vue climatologique, qui serait caractérisé par un « overshoot ».
I assume you don't need a translator for "cumulonimbus".
Tim Vasquez has this to say in his June 1 2011 re-analysis,
Based on the soundings above, my conclusion is that the maximum cumulonimbus tops were 56,000 ft with an equilibrium level of 47,000 ft, representing the tops of most parts of the MCS except near the edges. This agrees fairly well with the observed METEOSAT thermal data.
.....
This indicates that the aircraft was flying through convective clouds at about 0150 UTC and again from 0158 UTC onward.
Air France 447 - AFR447 - A detailed meteorological analysis - Satellite and weather data