I ask at the Chaosgroup side for a better Bongo support (motion blur, GI cache) and got the answer:
Bongo is unsupportable. It only calls the “-_Render” command for every frame. There is absolutely no way to determine if the user has typed “_Render” or Bongo has run “_Render”. Bongo is very limited in this sense. That being said, there is absolutely no way to programatically “capture” Bongo animations.
Is there really no way to access the animation data? Could there some possibilities implement please?