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.
"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!