Invitation mail language is different against auto-detect language.
The language of the teams invitation email will depend on the language settings of the receiver.
However, users who use Teams in English often receive an invitation email in other language.
I think that language is selected a tenant account settings .
Because We use Teams in the language detected automatically from a browser or an OS, we want to send an invitation email in that language.
We made the experiences and that has been confirmed by the Microsoft support, that the language for the invitation mails for guest is always in English and can not be modified by Customers. We need it in other languages as well and therefore we ask to make it configurable for Customers.
Also would like to be able to select the language of the text included with the invitation generated by Teams Meeting add-in in Outlook. Outlook is configured in one language but it doesn't mean that all my meetings will be in that language and others can read my default language.