Taken from https://meta.wikimedia.org/wiki/Research_talk:Increasing_article_coverage/Tool#Adding_a_location_filter:

I think this tool will serve better if it has another filter by number of views from a country or a region if that is possible. That way if some one is looking for articles to create in a particular language that is missing then they could also find the relevant articles according to their region. That way it is a better match on articles to be created. This offcourse could be an additional filter not necessarily embedded in the main logic.