::::::::: You are right and wrong ) BEA says "pilot modified autopilot setting to increase speed of the aeroplane in descent" The plane speed change is result of what he did do. BEA does not say what parameter/setting did he change in autopilot. If you set speed to autopilot, automation will keep that speed and it not change so much what is in data. But if you change something else result is speed change and autopilot allows variation of speed like in data. 
 :::::::::  In front page it should read exactly what is in BEA web pages and let reader to do own conclusions. If autopilot is turned on, autopilot is that who changes speed not pilot. Pilot put parameters to autopilot and autopilot controls plane.