Thanks for writing in. Just to be clear, "Translation Ready" means that the theme has a Text Domain and texts within it are connected to its text domain. That makes the theme ready for translation. X meets the said criteria so it is translation ready.
Translation can be done either by manual translation and single language or by using a plugin like WPML that has functions to display the theme texts in multiple languages.
Multiple Language Support is not a function of themes and it is also a big area to be covered within the theme.
With that said, the answer to your question is, yes, you need additional plugin like WPML for multiple language support.