Can this also be "you are so fun!"? I think the concepts work slightly different in Polish, right? So the concepts of "fun" and "funny" don't exactly match those of "zabawny" and "śmieszny" (the latter is a bit negative even?).
Yes, "zabawny" and "śmieszny" are not exactly the same, although the difference is very slight. If you want to state a positive opinion about some person, you usually use "zabawny". When you say "śmieszny" about a human being, it is usually in kind of negative sense.
"Zabawny" is someone you laugh with; "śmieszny" is someone you laugh at.
I only learned the difference now after 20+ years speaking polish..... I guess I've been subtly insulting my cousins for years now haha!
The translation on the screen is now "you are so hilarious". But in any case, is the response "You are so playful" incorrect:? Is there another Polish expression for being playful?
Google's suggestion is "figlarny", which seems quite good to me. Not an often used word, though. Another was "żartobliwy", but that itself comes from "żart" (a joke).