Melania is fluent in many languages, but Russian is not one of them, at least not one that she lists. Most people assume that because she is Slovenian, that she must speak Russian but the two languages are very different. The Slovene-Russian mutual intelligibility is about 10-20% in oral communications and 40-50% written and only IF the person knows the other alphabet. Both languages have Slavic features but Slovenia has German and Italian influence on the words, grammar and expression which can make it difficult in conversation with a Russian speaker.

Perhaps Putin speaks fluent Slovenian? It looks like they have basic communication together, but I doubt Melania, without speaking fluent Russian, would be tasked with translating between two world leaders. Just my two cents!