Why is "He smiles all the time" wrong? I know that "sempre" means "always", but this sentence sounds odd in English when translated as "always".
Yes, by itself it does. It's fine when it's part of a longer sentence, such as 'He always smiles at me' or 'He always smiles when we meet'.
As a native English speaker, I can tell you that "he always smiles" is not an odd sentence in any way. There are many, many contexts in which this would make perfect sense on its own.
Odd or not, "all the time" is a good translation of "sempre" in this sentence.
Well, it sounds a bit odd on its own to me too, so I went for "He's always smiling", which was accepted.
I think in learning a new language there needs to be a balance between translating what it says and translating what it means. There are often many different ways to say the same thing, but they have different nuances. It is good to know them all so you can say exactly what you mean and how you want, but we are learning bit by bit. Eventually I'm sure we'll learn how to say 'he smiles all the time' but right now it is 'he always smiles'. Happy guy.
Io vado in Italia tra tre giorni e ho imparato l'Italiano per... Tutta la mia vita, forse. Non sono benissimo quando scrivo in Italiano, mi dispiace :P
"He's always smiling" is much more likely to stand alone in English as a positive comment about someone than "He always smiles". The latter use tends to be context-specific, with emphasis placed on the 'always', such as in reply to someone saying "And I even saw him smiling today". But Duo is a strange beast...perhaps he has a dodgy predilection for male synchronised swimmers!