You'd either have to go through the scripts one at a time looking at the code or you could download the suitescripts / suitebundles folders and search those on your machine for references to that field to see what is updating it. Neither are pretty and you may not be able to tell with the suitebundle code if it's locked down. The only other way I can think is to un-deploy each script in turn and see which affects it, not pretty.