Why can't I filter by language code?
The support for filtering reviews by language code depends on the review site in question. As an example, Google doesn't provide us the language code of a review, while Tripadvisor does.
We're not able to filter reviews by language code on sites which don't report the language of a review, because we have no way of knowing what the review language is.
Rest assured that we do allow filtering by language code where this information is available on the review site.