How to build Custom Tracks

So I’ve taken up some track modeling recently, and I seem to be having a big problem with big discrepancies between the car in the in-game simulation and the track as drawn in TrackEdit. Does anyone have any tips regarding how to fix this, or does it just come down to “fudge it in the editor”?

What makes this frustrating is that this problem is not consistent whatsoever; some tracks I’ve made work perfectly fine, while others don’t.