If you wish to thange theme language you need to edit .po files for theme and pagebuilder.
Theme language file you will find: theme folder/lang/en_GB.po
Page builder language file you will find: page builder folder/lang/en_GB.po
Note: Some of our themes don't use pagebuilder, so you only need to translate theme .po file.
For editing .po files you can use plugin:
Also you need to select language via WP-> General Setrtings