Hactar can be localized up to 99% of messages.
Hactar localization is maintained in http://www.getlocalization.com/hactar. You need to register (free) to site in order to modify localizations.
Strings are quite stable do not change much. Still, during development I slowly add strings to Hactar and may remove some strings.
Localization site sends me notification on changes. If I do not seem to react, please notify me by mail or from hactar feedback.