First: are you translating using the tool?
it should allow you to add your language, it then shows all the fields with english on the left and empty field on the right, you can then enter your translation on the right.
Once all is entered you can compile using the tool where it creates all the files needed to be placed inside SolidCP for a new language.
“Peers” is pretty much the litteral defenition: Someone at your level.
So if you create a peer user as serveradmin –> it creates other serveradmins. If you create peer users under a customer it creates additional customer logins.