@Jeebs from eva.be
It seems like there has been a change in how multilingual support is configured for voice assistants. You no longer need to specify the language when setting up the voice assistant. Instead, you should choose a voice that supports the desired language directly from your voice provider.
For French voices with Cartesia, you should select a voice model that specifically supports French from the list of available voices provided by Cartesia. According to the documentation you've linked, you should look for a voice model that is labeled as supporting French (FR) and use that for your voice assistant.
If you're unsure which specific voice model to use for French, or if you're experiencing issues with the current selection, I recommend checking the latest documentation from Cartesia or reaching out to their support team for the most up-to-date information on available French voice models. They should be able to guide you to the correct voice model that will work with your VAPI setup.