What do you mean the operating language?
If it means the language of Outlook client, it is not supported now because the language of Teams meeting invitation is changed by the client language. In this scenario, the workaround is to change the language to English when user want to send Teams meeting invitation. Then, change back to Japanese.
If you mean the operating system language, it has no impact to the invitation language. You could change the language of Outlook client to English.
About how to change the language settings, please refer to this article.
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