Please excuse my ignorance of European languages but is that the same as Slovenian? If so, you are in luck. You can add a language at either the project, topic or topic content level. Check out this post for further details.
No that can't be done. The issue is that there are a whole series of language files in RoboHelp (e.g. stop list, ignore words, synonyms, etc.). May I suggest you put in a request for Slovakian via the wish list. You can access it here.