In English, "adventure" can be non-countable and likely should be used as a correct answer here
I was wondering about that also? To me, I love adventure is a bit different from I love adventures. I think for this example having either is helpful but I wonder if the Polish distinguish adventure as a concept as opposed to having adventures?
"Kocham przygody!" sounds natural to me, as it's the general notion of having adventures, I'd only use a singular one for one particular adventure.
Sorry, but I'm a bit confused. Your comment a year ago, Jellei, implied that you were accepting 'I love an adventure' but your recent comment suggests that you don't accept it. The system rejects it (and that it should be 'I love adventures'), so can you please clarify. Thanks.