The way the AI is currently trained doesn't allow for selecting the specific language you want the AI to speak via a tag or marker. Instead, the way you "select" the language is by writing in the language you want the AI to speak. If you are using a voice that is not native to the language - for example one of the pre-made or generated voices since they are English - the AI might have a slight English accent when speaking other languages.
To get the optimal results, we recommend cloning a voice that speaks the original language with the correct accent. This is especially important when dealing with languages that are very similar and share a lot of common words. This ensures that the AI has the most information to understand which pronunciation and language it should choose.