For that, you’d likely need to know Python better than I do? Then again - this works on a very simple basis. It only looks up the Unique identifiers + positions in one text file, matches them with the PCB file, looks a few positions backward in the PCB file to find the position (may vary a little) and then overwrites the PCB position line. I really love that Kicad is all text. Makes stuff like this much easier!
But - I don’t have any good schematic files with multiple sheets available (I prefer just making my schematic bigger). Maybe some of you could test this on multi-sheet files?