As explained in the GSX manual, Page 46:
The name of the .BGL used to customize the scenery is listed in the [GENERAL] section of the GSX .INI profile. It will include the complete path valid for your system but, don’t worry, there’s no need to edit it out before sharing your work, since GSX will only use the .BGL filename, and will ignore the full path altogether, it has been designed like this exactly to facilitate sharing of GSX .INI profiles without worrying about different paths. As long the currently active .BGL matches the name referenced in the .INI file, the .INI will be loaded by GSX, no matter the path.
There's no need to edit anything, GSX will only use the name of the .BGL, and will ignore the path.
I made this test just to be sure, and added a completely bogus path on purpose, like this:
\\?\H:\DSAJDAHSKHAKJDHK\offf\dfsafas\fsad\aaaaaa\2222\APX50150.bgl
When the airport .BGL, on my system, is here:
\\?\E:\MSFS\Official\OneStore\fs-base-genericairports\scenery\0601\APX50150.bgl
And GSX loads the .INI file just fine, even when the path points to a folder that doesn't exist, on a non-existent drive letter, because the only thing that matters is the .BGL name ( APX50150.bgl )