You are using the en_US_DEBUG locale. This file is 'lessonbuilder/tool/src/webapp/templates/instructions/multimedia_en_US_DEBUG.html'. The File you have to translate is 'lessonbuilder/tool/src/webapp/templates/instructions/multimedia.html'. You have to add your locale to the file name for your translation. If your locale was 'fr_FR', the translated file name would be 'lessonbuilder/tool/src/webapp/templates/instructions/multimedia_fr_FR.html'.