Today's bahasa Indonesia

The sentence, "It was hard day", and particularly on the word "It" would naturally be understood to refer to a specific day, so in English, it can also be said: "That day was a hard day".  <- And the literal translation of that sentence is "Hari itu adalah hari yang berat"

Day: Hari <- This is why the word Hari comes twice.

"cahaya yang musim dingin malam hari ‎melihat sunyi" <- This isn't close to "The night light of cold winder looks even lonesome". The closer translation would be "Cahaya malam pada musim dingin yang dingin terlihat semakin sepi" <- It seems a rather difficult translation perhaps? That's because I'm translating two words: Cold Winter

-Cold: Dingin

- Winter: Musim Dingin

This is why the word "Dingin" comes twice

So that is why, I feel that the most correct translation would be: 

It was a hard day <-  "Hari Itu adalah hari yang berat".
The night light of cold winder looks even lonesome <-  "Cahaya malam pada musim dingin yang dingin terlihat semakin sepi" 

I hope this helps. It's quite poetic btw! :)