Two language settings in your MARA account can be used to change your reply language:
General reply language for automatic replies & pre-generated reply drafts:
You can change the language in your automations screen and create an automation rule/adjust an existing rule. At the bottom of the rule settings you can define your preferred languages (e.g., always in the guest’s language, or only in the guest’s language for certain languages and in English for all other languages).
For manually generated replies using the “Generate reply” button in your inbox:
When manually generating a reply in your inbox, MARA uses the language selected in the top right corner of your reply field. To generate a reply in a specific language or change the language of the generated reply, simply select your desired language in the drop-down.