Well, I managed to find a save editing solution to this problem after all.
Permanent crawling because of handcuffs fix with save editing:
Remove handcuffs ingame from the slave if they still have them, then save. Open the save in notepad++ or some other text editing software. Find the first name of the slave that has permanent crawling, search the next instance of "restrained": and replace "restrained":"cuffed" with "restrained":"none".
When I loaded the save, the game automaticaly detected that this slave should not be crawling and changed back to normal.