Glad this is up! My favourite movie of 2019.
All of that is OS, though, isn't it? Where is his IC perspective here?
Looking back, I think @MWollaeger is onto something. In fact, Rian Johnson basically spells out the perspectives for us with that Go board.
Despite clearly being good at it, Marta doesn't play to win, she says she plays to make a pretty pattern. Harlan, of course, (jokingly) knocks the board over so that he can't be beaten again. When the wrong dosage is given to him, Marta plans to do the right thing -- but Harlan concocts an elaborate lie to protect her from the fallout.
When Ransom comes into the picture, he pretty much adopts that same perspective: helping Marta concoct an elaborate lie to protect her, albeit with a caveat -- he's playing the game (or the murder, if you will) to win, so he will be exonerated in the upcoming investigation and Marta will go down for it. It's pretty much the same perspective that Harlan had: you play the game to win, no matter what.
And, of course, the big change: the honest-to-a-puke Marta ultimately doesn't play to make a pretty pattern (aka protect the family), she lies to Ransom so he will confess and she will be exonerated. By the end of the story, she plays the game to win just as Harlan did and just as Ransom did -- and she still beats them.
Admittedly, this is my simplistic way of defining the two perspectives, but I think it's clear that there is some kind of hand-off. While Ransom is an entirely different type of character to Harlan, the perspective seems to be the same.