However, I edit AFCAD in order to fit the position for AI traffic in regard of the lines painted on the ground in the certain airport scenery. My aircraft also should be stop there regardless the door position.
Your aircraft with GSX will never park in the same position used for AI, since AI use the same, unrealistic method as the standard Go To airport, which will place the aircraft reference center (its 0,0 position, as modeled in 3ds max ) in the center of the parking, which is almost invariably wrong, especially when parking a smaller plane into a large parking spot.
That's why we have a separate Stop position to begin with in GSX: precisely to prevent this problem, at least for your airplane.
And, altering the AFCAD to fit AI better, won't work across different AI types, unless you are editing parking spots that would accept a very limited number of AI types, all with similar dimensions.
The method used by GSX is the one that most closely matches reality, which is using the door position as a reference, by trying to have the door ending in a predictable situation, which will likely results in different positions of their front gear on the markings, exactly like in reality, since the whole point of having ground markings in different positions depending on the aircraft, is to have the jetway move as little as possible with different airplane types, and that's of course suits GSX very well, since you can be reasonably sure that, if you tested the jetway with a certain airplane type, it will likely work with other types, since their door would end up in the same place of the door of the airplane you designed the parking with.
About ground markings, it's not guaranteed they would be compatible with the GSX strategy, especially if they are custom textures on 3rd party airports, since GSX cannot possibly have any idea how different airplane stop positions were made by the developer and how they were placed on ground. And even assuming they are reasonably compatible with the concept of having the preferred door always in the same position, they might have not be made assuming the same preferred exit. For example, if a scenery has markings which are made with the 747 position correct for the usage of the L1 exit, but your 747 has been configured in GSX to use the L2 exit instead, they will surely won't match, even if all the other airplane types might work perfectly.
For example, when we made the last KLAX update with SODE jetways, which comes with a GSX configuration file, we ALSO remade ALL ground texture markings and placed accurately, one by one, in the scenery, to match GSX logic perfectly. So, if you want an example of an airport perfectly integrated with GSX, look at KLAX. But, again, don't expect AI would behave the same, since they don't know anything of the GSX Stop position.