I can only give you a rough outline of what needs to be done. This would take a good deal of coding.
When showing a person:
- Get all the related films
- Loop over the related films and get the data from each film
- Build array(s) of data that can be used with either php usort() or php array_multisort() – I would use usort()
- Sort the array(s) using either usort() or array_muultisort()
- Loop over the sorted array to output the data
Like I said, I would build a function that works with usort().
ACF has a basic example of using array_multisort() here https://www.advancedcustomfields.com/resources/how-to-sorting-a-repeater-field/
