Translation folder contains different locale.json files in which labels are kept.
As you run main.js script it will output all those labels which aren't translated in all languages(i.e If label is not translated in all language) in output_en_US.json file
merge.js file will merge newly translated labels to already translated labels you have to keep all newly translated label files in merge folder and already translated labels to translations file
Below are helper files for test: mergegenerator.js file generates new translated labels for different locales in mege folder for test
jsongenerator.js file is generates translated labels in each local file for test