Thank you for your answer. I still don't understand why the songs aren't in the playlist, though. The maltese and ukrainian songs are both on Spotify. I still don't understand why the armenian song appear twice either.
I've seen that the playlist is not made by Spotify but by a guy named Scott Elk. He probably did a mistake adding twice the Armenian song and forgetting the Maltese and Ukrainian ones. You could try reaching him out personally and advising him about the mistakes.