Populating AES structures requires passing pointers to strings and various unions and packed structures INTIN/ADDRIN, etc. I remember this being not so simple with the GFA I had. Maybe later versions improved interacting with that kind of thing.

Ah yes, sounds like 3.0 added all the proper AES structures and a bunch of other goodies https://www.atarimagazines.com/startv3n6/gfa_basic3.html