In reality, the armour technology of the British Challenger is world-leading. Plus, Challenger always sticks to the design principle of prioritising protection and survivability, but in the game, the Challenger series tanks feel as fragile as paper when it comes to survival and defence.
I Agree and disagree with you for the following reasons:
I Agree becuase:
the Challenger series has sustained minimal overall losses throughout its combat history, in gulf war ( 0 loses ), iraq war ( 1 loses ), and russia-ukraine war ( 2-4 loses ), that definitely does not reflect the tank solid history and its operational service and reliability in war thunder.
I disagree because:
In war thunder, some of that in real life realism is reflected in game as a coding designed scheme, a simulation that does not simulate real life fully, taking into account details, classified info, and historical reports, even tho it resembles a somewhat basic idea of how it works in real life, how it protect, and advance, even tho that does not mean its completely Undestroyable tank, even there is alot of tank with historical inaccuracy and design flaw by default in real life, those are Designed like that by default,
As i see it; Challenger series of tanks are well presented in war thunder as much as possible, if there was a released kind of information publicly available it will be definitely be used to improve its historical accuracy and reflect it in war thunder.

classified dokuments?
Even its not sekrit, we get the rotating floor. :D