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.
The Turbo v2.5 model has an experimental feature, available via API only, which allows you to specify the language code for your generation. Please see the API Reference for full details. As this is an experimental feature, results may vary. This feature is not available for our other models, and providing a language code in API calls using other models will return an error.