It's better if they are but it's not mandatory. Reviewing means you attest that a word or a sentence is 100% correct and matches with the other translations. https://trac.wildfiregames.com/wiki/Localization
As you can see at the bottom there are dedicated pages for each language where you can add more rules. I can create a German page if you want.
You need to install and compile wxwidgets. Which is why I suggested you use the DLL instead.
See also: ⚙ D3211 Add a script to download compile and install wxwidgets (wildfiregames.com)
Actually 0 A.D. was supposed to be the name of the franchise (e.g. Age of Empires)
The game you play is called Empires Ascendant, and the Suebi, Imperial Romans, Parthians ex were supposed to be Empires Besieged.