You are assuming the scenery has a problem or need fixing, when in fact it doesn't, and the ONLY two parking spots flagged as Cargo in the whole scenery are F21 and F22. No other parking spot if flagged as Cargo so, from our side, we do it correctly.
However, you must understand that not everything can be controlled by the airport: if MSFS decided to park a Cargo aircraft and, for example those gates are already taken, it WILL take any available parking spot which is big enough to accept the airplane. Sure, it might be possible to play with sizes but, that might prevent Heavy passenger airplanes to ever get there, so that method won't always work.