First question…

When the batch processing has finished, what does the pop up window say?  Does it tell you that some images were cropped tighter in camera that the settings in the preset?  That is usually the cause for inconsistent cropping. What happens is if the the edges of the crop would be outside the edges of the image based on where the preset tells it to put the face, those images then have to be cropped tighter than the preset wants to so the crops fit on the original image boundaries.

If this is the issue then you need to shoot looser so the crops all fit within the original image boundaries. Don’t try to crop in camera and then try to make the same crops in the software.  The software needs room to work.

So please run the batch again to see what the message says when it is completed so we know if this is happening.

Let me know and then we can proceed from there.