there
WAS an increase is clearly shown by two paragraphs in the note:-
At 2 h 08 min 07.....the level of turbulence increased slightly and the crew decided to reduce the speed to about Mach 0.8.
I agree with "BOAC", there WAS a turbulence increase but, since they only elected to reduce speed at 2h 08, the level of turbulence before that time must have been very benign ideed.
This is very close to the LH crew testimony :
Flight LH507
Flight LH507 (B747-400) preceded flight AF447 by about twenty minutes at FL350. The crew reported that it flew at the upper limit of the cloud layer and then in the clouds in the region of ORARO. In this zone they saw green echoes on the radar on their path, which they avoided by changing their route by about ten nautical miles to the west. While flying through this zone, which took about fifteen minutes, they felt moderate turbulence and did not observe any lightning. They lowered their speed to the speed recommended in turbulent zones. They saw bright St Elmo’s fire on the windshield on the left-hand side.
Imho, all this means that those who chose to divert to the east of track had to deviate more, for a longer time and suffered more turbulence.