There are several ways for developing a mod that can be closed to the real car, no doubt. The GP3 was the unique in the mods we developed where Chris spent months and months in entering thousands of real data into the spreadsheet of Borda and, time by time Borda improved the spreadsheet and Chris "moved" data into the new release (and it was something crazy, because there is no way to update the spreadsheet to a new one keeping data already entered...). In the meantime and after Mr.D and later also another engineer of another GP3 team validated all data into the spreadsheet and how they were converted to rF2, also with the feedback of few real drivers of the 2017 GP3 season. Some more driver tested the mod also in 2018.
I think this is the best way to develop a mod, maybe it can be excessive for a game, but some driver uses rF2 + GP3 for training...
Again I agree with you that is not mandatory, in fact the Palatov D4, for wish of Palatov himself that is an engineer and designer of all his cars, with also the patented suspension system of his cars, never considered a good way the use of the spreadsheet for some limitations in the code of rF2 exactly addressed to his chassis and suspensions, so he preferred to check directly data entered into the physics files of rF2 and, also with the help of his factory driver, to test the mod and asking for fixes. And also the D4 is a high quality mod for the physics, no doubt.
About the F319, we need to look at the first true pack of official documentations, to have a clear scenario of the differences vs. the GP318: currently there are only info here and there of what Dallara and other involved entities discussed in Monza for the first time and later.
Verba volant, scripta manent!
And there will be also several changes into our reference team, so really, at the moment I have no idea if we'll jump into this new adventure.
I'd add a lot of """"""""""" to selling tool for what regards us... I know selling is only a way of saying, but it has nothing to do with us!