I truly wonder what dedication one would have to have in order to learn 54 languages. That is just the most impressive even if you know the language at a basic level. Quote from the article: "including one who spoke 54 languages with at least some proficiency."
Once you know Russian, Polish and Serbian - you know all Slavic languages basically. Maybe Albanian will give you some problems. That's like 15 for the price of 3.
There's probably similar shortcuts in other language families.
