GSX has the ability, internally, to override its default strategy of "placing the airplane preferred exit in the same place", and use a custom "table of offsets" for each single parking, to adapt the stopping position to the actual ground marking textures which might be different for every scenery, developer, etc.
We used those in some of our earlier sceneries, when there wasn't a custom Stop position that used the "placing the airplane preferred exit in the same place" strategy in GSX, but that was obviously a pain to setup, because you had to check every different texture used by every scenery, figure it out the pixel/meter ratios and set multiple stop positions for different airplanes. It was lengthy even for us that MADE our scenery, so I could only guess how much more complex and annoying it would be for end users of 3rd party sceneries, and even with a more user-friendly interface, it will take A LOT of time to customize an airport that way.
Lots of users don't even do the very simple SINGLE custom Stop Position we have now, I'm not sure how many will take the time to customize SEVERAL custom Stop Positions for each parking.