GSX keep detecting default afcad instead the custom one, even if i put the afcad inside the virtuali folder.
That's because that airport .BGL is abnormally large at 40MB, because the developer decided to put several extra things inside of it in addition to the bare airport data. It's not a very good idea, because if they wanted to update even the smallest thing like an ILS frequency or a taxiway name, they would have to distribute that large file, so most developers usually try to separate the airport data from other things like 3d object, and in order to speed up the airport cache regeneration, GSX automatically skips any file larger than 30MB ( it was 4MB in FSX/P3D).
You can raise this limit by adding this line in the %APPDATA%\Virtuali\Couatl_MSFS.INI
airportCacheMaxBGLSizeBytes = 50000000
I've set it to 50M ( 50 millions bytes ) in this example, so it would take your 40MB file.