E in EFM means external. All this means is the calculations are done not by the A- or S-FM ED-made architectures. The range of fidelity is the widest with EFM from superior to tragic. While FM is an important part of a flight sim, systems modeling is the lion's share of the product. Most of the aspects of the sim you name: radios, displays, animations, engine, hydraulics, radars, weapons, sounds are all systems and not part of the FM.