The plugin is i18n translation ready. The .pot and .mo files are located in the “languages” directory of the plugin. The text-domain of the plugin is “multi-rating-pro” for the pro version and “multi-rating” for the free version.
Remember to name the language translation files in the format <plugin name>-<locale>.<po or mo> e.g. “multi-rating-pro-en_AU.po”. Place your language translations files under the plugin languages folder normally under wp-content (e.g. wp-content/languages/plugins/multi-rating-pro-en_AU.mo).
See here https://developer.wordpress.org/plugins/internationalization/localization/.
The plugin has custom text settings that are saved in the database. You will need to disable the custom text settings under the Advanced settings so that the default source text is used instead. Once disabled, make sure the custom text settings are readonly.