You probably could do an objects both for original a translated texts. Then you will gonna need some condition and set it to the objects. You can reverse it for the translated texts so eiter one or the other language is gonna be shown.
Now the tricky part: You will have to use the config.ini file ( or well any other file ) as you can't relly here on the save data and you need to store the information somewhere else. And that's what's config.ini for.
What you need then is to learn how to write and read from a file in Lua. If you change the language in the menu you would write that in the config.ini file. Something like language = english.
Then on the reading part ( a script that will run on the game start ) you would read the config.ini file and based on the information set the language condition.
There's an example script from AFRLme on the Visionaire wiki, but you don't need it that complicated just for setting a language.
local file = io.open(localAppDir .. "config.ini", "r")
for line in file:lines() do
if string.match(line, "language") then
if string.match(line, "english") then
game.StandardLanguage = Languages["english"]
Conditions["menuLanguageOriginal"].ConditionValue = false