SMS for WooCommerce has built-in support for the WPML plugin. Note you will need the WooCommerce Multilingual as well as WPML, together with the String Translation and the Translation Management modules, which are part of the Multilingual CMS package.
You can add more language from WPML > Languages, There you need to click on Add / Remove languages, then find that languages which you want to add for translation.
After adding the languages, navigate to WPML > String translation, there You can find a dynamic string by search and you can filter a string by plugin. you can do translation of string by clicking on edit icon on particular language.
To translate the SMS messages content, search for the string translations that starts with smswoo_