The Building API (for placing static objects in scenarios) is broken through and through.
EF2000/F22 have their building graphics integrated into terrain supershapes. So with these games, the building API is just a facade that redirects collision events to the terrain.
Ace Combat 3 does not use the building API yet. As a result, stuff like flak bunkers cannot be interacted with, cannot have AI, and isn’t culled on rendering (neither distance-based nor frustum-based).
All this needs to be put straight, with the aim of having destroyable flak bunkers in AC3.