The language attribute on the Topic Set in Search Administration can limit the topics you browse by country. If a topic set does not have a language associated with it, the topic set will use all languages.

You can set the User UI Locale for all queries and results, by selecting the Knowledge Settings > Languages > Use UI Locale check box.

To control topic sets by country, use the /atg/searchadmin/repository/service/TopicService/ localeTopicSetMap. If localeTopicSetMap is set, it overrides the language properties associated with the topic sets.

The Locale Code is either a language code, or a language code and a country code, and a colon-delimited string of topic set names. A topic set can be associated with more than one locale. If associated with a language, the topic set is available in all countries where that language applies. For example:

en=topic set1:topic set2,de=topic set2:topic set3,en_US=topic
  set4,en_UK=topic set 5