I wish SAP would make over life as easy as it looks on screen. Here the problem is what ever appering on screen is through structures for display and it have filters to show how it looks like before reading a master data again , but when we try to use FM to fetch information it do not follow same logic as display , it fetches the information for current sutuation , FM for configutration fetches the current values on CUOBJ and you end up getting whats not actualy visible or applied on a order object.
Only option i can see here is get an expert ABAPer and sit with him/her to figure out in debug what structures being used here and how to implement same logic in an custom program.
Alternative , generate a spool and save it for later use , specialy when you have change sales order with config values, fetch the old spool and print it for your comparision.
Thanks
Ritesh