This tutorial is very easy and does not require technical stuff.
All you need to do is translate the language of the launcher by editing Translations.xml.
Open Translations.xml in notepad or notepad++.
Replace the necessary strings you wish to translate.
Important: Be careful not to delete <> from the nodes or you'll receive errors. You can check the errors when you start the launcher and see /logs/ folder.
Important: We also support multiple language translation. However this is by request only. This is a paid feature.