When I first made the mod, I wanted to find the hdv lines and talent lines that made the best, genuine difference to the performance, so I did a lot of trial and error testing.
In the talent files I commented everything out except speed and watched the AI behaviour & recorded their lap times as I kept changing the speed number. Then I commented everything out except aggression and tested different numbers, and so on with each line of the talent file. Only aggression and speed made any discernible difference, so I un commented them. I believe minimum skill still affects the occasional poor lap that an AI can have (if I remember correctly it might be connected to AI mistakes in the plr file), so that also is uncommented.
But for the others, they had no effect on the results in my mod so I left them commented. It was also a way of eliminating any unknown or unwanted effects.
Reiza is now using courtesy so that is back in, and they have also added tire management and start skill.
But as far as I know, the others still do little or nothing.
I seem to remember there was a time when composure or crash worked, but I might be thinking back to rFactor now, and I couldn't see any effect when I made these files.
EDIT I should add that commenting a line out is not switching it off, just reverting all cars to default setting for that number.