Sorry for the slow response! It was, indeed, late in Jolly Old Blighty and then I didn't get a chance yesterday.
I think this is part of the problem. We need to try and figure out specifically where that 'lie' thing sits in the storyform. Is that part of the Overall Story or is it just a Main Character thing?
Because, broadly, I agree that it doesn't much touch the court case, but it does have occasional cross-overs (it ruins his whole strategy for the case, which throws the whole OS 'plan' into chaos). And the more I think about it, the more convinced I am that the whole lying thing is firmly in the OS. In fact, I had a sudden brainwave last night about the whole thing:
The OS is basically about a whole bunch of people who lie constantly to influence the court case or the legal stuff in their favour (the woman he sleeps with is trying to expose him to the board; the other lawyers are trying to win; Fletcher is trying to establish this fraudulent strategy with his client; Tilly is lying about the WHOLE thing). So, if conflict is made up of two incompatible things, is there any stronger conflict for an OS made up of liars than having Tilly's lawyer be someone who CAN'T manipulate the situation to his benefit? That seems like pure psychological conflict.
You also then get that Elf-like or Paddington-type comedy where someone is saying the kind of comical things that he shouldn't. Only, instead of being naive like Buddy or Paddington, he just literally can't stop himself from blurting out these hurtful opinions. So he's offending every single person almost every minute with this kind of immature, unbelievable behaviour that is literally rooted in his psychology -- or how he's thinking.
And then if I have to separate the MC throughline, I think that is ENTIRELY about him trying to work his way up the ladder and boost his career so he can be THE lawyer. It's why he sleeps with the woman; he puts his son off, etc. And then that leads to his eventual change of basically abandoning the case in favour of pursuing his son (which feels much closer to the IC perspective of 'you need to be better,' or something to that effect -- I'm trying not to use the word 'honest' because I don't know how separate that is from the OS).
I haven't thought much about the goal, but I'll give it a think and update later! I just had to post the above because I thought about this last night and it suddenly hit me like a big old Dramatica thunderbolt!