Yeah I'm 99% sure that the personality system hasn't been touched since EA release except for integrating the bugfix for personality reset from game start.
Somebody coded the basics for a personality system and it hasn't been touched since, probably because the devs didn't think it was important. It appears that personality has no effect on NPC AI, regardless. Honestly, given the jank in the dynamic system, it'd probably work better if they just made it static and added more personality +1/-1's in character creation, followed up by hard changes in response to specific actions like raiding villages or executing lords.
I sincerely doubt that anyone intentionally made it so the only way you can get to Calculating 1 is literally persuading 50 clans to join your faction (just rechecked the math: 20 Calculating per persuasion and 1000 threshold for Calculating 1).