I realized that when I came to the sentence "Kanapka jest smaczna". I made the same mistake and translated it as "The sandwich is delicious". Luckily, a note popped up and said that "smaczna" is not as strong of an adjective as "pyszna" is, which means delicious as you said. I appreciate the helpful response!
Zupa jest smaczne - soup is tasty was accepted, yet wino jest smaczne 'wine is tasty' was not. What is the difference here please?
yummy (comparative yummier, superlative yummiest)
(colloquial, lighthearted, often childish) delicious.
Which is exactly what my thought was, that it sounds kinda childish, which would look a bit inappropriate given the fact that the 'yummy' thing is wine ;). But if you really think that it should be accepted, by all means, you can report it next time you see this sentence.