i feel like when i started to learn a bit of portuguese, which is mostly intact vulgar latin, that a circle closed because SO MANY WORDS were related between portuguese and slavic languages, i literally did not realise that half of what you call "slavic" is actually latin and the slavic words are probably obscure things in the shadows of the language, colors, rather than forms
after spending so much time in bulgaria and former yugoslavia it was shocking to me listening to people bantering in portugues, like, my god, they have the same set of phonemes, just a different way of using them and numerous similar words, like "tu" in yugo is basicaly the same meaning as "tu" in portuguese (it's an informal "you", similar to voce, they abandoned the genderless version in formal speech you have to say "minha senhora" or "senhor" for you most of the time, which is gendered
there definitely is a certain point at which you may not be fluent in many languages but you have enough basic building blocks that you can catch the gist a lot of what a person is saying, by tone, by phonemes and syllables, and other things
enough to say that generally, you guess right about the intent of an expression when you take it all in at once