NarikTranslateLoader load translate files from path that specified in ConfigService ("translationsPath"). For example if "translationsPath" is "assets/i18n" you should have a folder for each language in "assets/i18n".
The third parameter in NarikTranslateLoader's constructor is default translate items. For example in this sample, if defaultLang is "en" the file "assets/i18n/en/app.json" loaded as translate items. Other translate resources will be loaded whenever they will be necessary. They are identified in metadata. The rule for metadata translateItems are the same as default resources.