For some reason, CKEDITOR.editorConfig()
is not called once CKEditor is loaded. I think it is only called when instantiating an editor.
Therefore, I had to modify the global configuration directly:
CKEDITOR.config.customConfig = false; //no config.js
CKEDITOR.config.stylesSet = false; //no styles.js
CKEDITOR.config.defaultLanguage = 'en'; //default language
CKEDITOR.config.language = 'en'; //ui language