there are very different ways of communicating in Sweden and in Poland
For sure. It would be very weird if they were similar.
As a non-native speaker of Polish 'Co ty?' is one of those phrases where it's not the words, but the melody it's sung to that matter. It can be playful and affectionate or hostile and dismissive or just a kind of an empty answer when the person can't think of any other response.
I'd have to hear the 'co ty's in question to have any opinion on the intent of the speaker (and member the same intonation pattern can have different meanings in different languages)
When Polish people think you're wrong they let you know pretty directly but that doesn't mean they don't like you, friends can get in what look like pretty heated and hostile debates but it passes over pretty quickly and they don't hold grudges about it.