I approached CTD’s like this: I know how unstable AI traffic made FSX.
I had 1000’s of liveries and flight plans for AI traffic in FSX and when ever I had a CTD I could fairly easily find the cause being a problematic flight plan or livery.
I haven’t done much with flight plans and AI traffic in MSFS, but I have taken a look at how it works and the Offline AI Traffic system is virtually the same as FSX.
My personal opinion: “Bad” AI Traffic flight plans/data (like no destination, aircraft unable to do approach, unable to climb/descend to certain altitude, livery problem etc etc…) make MSFS CTD, or cause an error within the sim that makes it unstable and then something else causes a CTD.