No kidding... the first four emotions so far have been fear, anger, shame, and sorrow. And of course now happiness is introduced in the negative
In such a general statement, I don't think you can talk about "a joy" (jedna radość, jakaś radość?)
I don't hear anything extraordinary, but maybe that's just because I'm a native.
RU: Zizń eto nie tol'ko radost'. This category of emotions and feelings is so similar to Russian, I would almost go as far as mutual intelligibility. Almost.
Not exactly. "radość" is more temporary, the closest translation is "joy", even if it's not used that often as "happiness". "szczęście" is a longer state of feeling genuinely happy.
I changed the main answer to "joy".
EDIT: Please put this on "Hold" until I've checked it further: my scorecard hints at a User not properly awake Error rather than a Duo fault... 8-/
[The hover hints for "radość" currently list happiness/joy/delight as possible translations - but Duo rejects "Life isn't just happiness", wanting only "joy" (the main answer).
So is "happiness" a possible answer or not? Please make up your mind, Duo!]