I'll tell you something: I've more then 5 customers running on a fury écu on a s54 engine with dual vanos. Vanos always active, even on idle. Afr spot on, nice flat torque curve between 365-400 nm and 365-410 hp (some stock engines, some build with 302/296 cams ect) all on 1 fuel map strategy. Your vvt maps decide the position off your cams, so if load axis of vvt and fuel map are the same, there is definitely not a need for a second fuel map. As you have a m50 with a simply on-off vanos, thing getting even more straight forward. You're making it yourself way to hard.
Have done m52b25tu engine ass well, on another ecu brand, same story.
Make it yourself easy, ditch that second fuel map, let your vanos switch at a certain rpm (which you can easy test on the dyno) and if you choose to let it switch on a certain tp as well then set your load axis to tp as well of the fuel map, otherwise you make things complicate for yourself