You are right -- It seems its more quest based then actual corruption - corruption (depravity) can be set to max without it changing. I think you are looking for more of an end game save or you may be able to modify things to move it along:I have use that cheat button, but it's not raise the corruption level'n......
QGen editor - if you edit the 'New game - the Options' you can toggle the quests manually
- for example change 'set angelinaqw1 = 0' to 'set angelinaqw1 = 1' (See 'Quests' to figure out the last quest stage)