[Other Question] Change the language

I am trying to translate a game that i am developing starting from pokemon essentials. I did "extract text" from debug mode and translated something to try, then I did "compile text" and then I added the .dat file to the data folder and added the language in the "settings" script. But when I start the game it remains the language that was previously (English) because it is set as default. How can i change language?

You can change the language in the ingame options if you added one

How can i add it?