Hi ram2 ra,
Thanks for reaching out to Microsoft!
Unfortunately, there isn't a direct way to specify a different language for the auto-response through the API itself.
I tried changing the regional language of the room mailbox and creating an event from the GUI, and I was able to get the response in the regional language settings applied to the room mailbox. However, when I created an event using the Graph API, the response was still in English. This seems to be a product limitation.
As a workaround, you might consider setting up a custom auto-response template in your preferred language and configuring the mailbox to use that template.
Since this feature/functionality is presently not available, you can submit a feature request idea using support link, which will be monitored by Microsoft team and make the enhancements to Microsoft Graph APIs.
Hope this helps.
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