The info isn't real though. It is guesses.
The info you call guesses here is comes largely from Focke Wulf's design specification documents produced during the design phase of the Ta183. I think specs that have come out of such an extensive engineering process are a bit more than just guesses.
If HTC decide to add stuff based on calculated numbers rather than fight test numbers that is up to them, but I would rather they did not.
I agree but it isn't always possible. There are already in the game aircraft which have their performance based on calculated numbers AFAIK. The OP was asking for "what if 1946" arena. Ta183 indeed qualifies as far as "what if" goes. What qualifies for LWA today is irrelevant in that regard. I remember posts about a Con couple years ago saying that "1946-type - what if arena" was one thing that HTC had been thinking about along with Korea and WWI. So it isn't something that HTC has dismissed offhand weather one likes it or not. Right now, I don't think even folks at HTC know if that sort of thing ever gets done or not.
Personally, I wish they'd focus on the work horse units of WWII.