So I know you are having issues with the ai so I might have a fix, I saw that the grid was closer yet farther away than normal.
So first, try making the grid more open and not too close, that might be causing the main issue.
Otherwise from the AI issues. the track is well put together, I like how its not like the other tracks and more original.
I could also give you a better road texture and maybe help on the barriers, (The hitboxes ain't well lets agree).
But otherwise from them, for Race Track Builder, bravo man.