Not entirely sure what is meant here - you can apply LightMix and VFB post-processing in C4D, then render your image sequence, and the LightMix and post-processing are "baked in" to that image sequence, already applied.
If you mean, can you render an image sequence and then adjust and change LightMix and VFB post-processing on the image sequence itself AFTER rendering, then yes at the moment the batch script is the only way to do that (also, this doesn't allow the animation of the LightMix and VFB processing, just allows you to apply the same effects to all images in the sequence).