Please show me where I'm contradicting what private server developers have said? I get the feeling from your posts that you're not a theorycrafter (nor do you know anything about private server development or bug fixing), that you've not delved into that world where developers and addon creators/theorycrafters have always had a back and forth relationship. Or do you believe that all theorycrafting is based on "purely made up guesswork"?
The majority of theorycrafting stuff is reverse engineered in game, as in they figure out the formula from the ingame numbers themselves and it gets documented, tested and confirmed. A lot of it is a two way street between players and blizzard developers too. I think that I have to explain this means you're outside the theorycrafting community and you're going to play hardball asking for me to dig up something to please you, which I'm obviously not going to do.
If you want to do your own research you would understand why these "Oh its a private server so it must be wrong" are just as bad (if not worse than) those saying "it's a vanilla private server so it must be right".
https://wowwiki.fandom.com/wiki/Normalization
https://vanilla-wow.fandom.com/wiki/Hit
https://vanilla-wow.fandom.com/wiki/Spirit
https://wow.gamepedia.com/Armor
Many sources list this basic information, nobody is needing to "guess" the basics that have been well documented and known since Vanilla, with every change and variation also documented and understood.
Edit : And you could for example take those numbers from Vanilla, dump it into a spreadsheet to say calculate armor/damage reduction and then apply the results of those numbers and compare to a private server and see "oh my, they are correct".. Or you could swing at a boss on a private server and collect data, then use the armor formula combine with the ability formulas and your characters stats and calculate accurately the armor of that boss based on the damage dealt, and compare back to vanilla numbers and find that your vanillla numbers and vanilla formulas are correct.
Theorycrafting works, nobody is making shit up out of thin air with the basics.