In general terms you should make sure the same language is used for all content.
In special cases where text is written in a different language from the rest of the page, use the tools in the publishing software for declaring the change of language.
The “Language” option in the publishing software is used to indicate expressions written in a different language from the main language.
Delete this recommendation if the publishing software does not have a feature for this, and ask contributors to limit the use of terms in foreign languages.