Well I don't want you to waste your time unduly if its not workable. I'll try and offer my observations as best I can.
I've included some pictures and a short replay comparing my chicane line to the AIs. I used the third place AI in this example as his run through the chicane can be seen at the start of the replay and mine at the end. His times in sectors 2 and 3 are also about a tenth faster than mine even though his sector 1 is a 23.8xx while mine is a 23.09x.
The attached pictures compare three things. The speed through turn 2 and the apex of turn 1, car position at turn 1 apex, and line through turn 1. The speed is obviously a big difference with me being 11 MPH faster at the apex of turn 1. You can also see that the AI line makes for a slightly better exit but that's less important for this chicane as its a short run to the next corner and its clearly much better to carry as much speed to turn 2 and compromise it a little bit.
The turn 2 speed comparison is measuring the point when the cars go below 61MPH, reach minimum speed, then go above it again. I'm clearly compromising my run through turn 2 but I can also drive this better if I tried without losing my turn 1 speed. The AI clearly spends way more time below 60MPH through most of the chicane that his better exit from turn 2 offers little advantage overall. The turn 1 line is showing the point of turn in, apex, then turn out.
Looking at this onboard of a real Champ car I think my line is pretty much the same. Turn in is kind of a progressive curl towards the first apex in the chicane instead of it being just a straight line braking then later turn in. The real life driver takes turn 2 better but I could too if I practice more and did some set up changes which I haven't. The AI seems to stay way more to the left and turns in sharper to turn 1. If I do the same thing I tend to lose equivalent time to what the AI seems to lose.
I was considering writing new AIW's for Vanport as I am not happy with what we have
Overall I don't really have any other complaints for the AIW as a whole. Its actually quite good how consistent the AI is compared to a human pace everywhere but that one corner. The AI also seems to really be less prone to bashing you about in this AIW so its a really good one for doing long-ish races even with the turn 1 issue.