What do we do with the patch on pc?
You can move that in, too. That folder is specifically designed for patches- if a saved game can't find the right place in a script, it starts rolling back to somewhere it can correlate the save with the script. the Old Game folder is a previous version of the compiled scripts to work as an in-between bridge between a save and the current script, increasing the chance of success. If it still can't correlate, then you get the normal error about "couldn't find a place to stop rolling back."