I believe this is not determinable at this time on whether it's a bug or not, time-zone withstanding, joined several different daytime only servers and experienced night in all of them on US servers while it was still early/daytime in real life as well. What I don't know is if it does turn out to be a bug - is it server side or client side.
Also - can you please do your best to fix this before US eastern early evening tomorrow or no later than Friday? Reason is, today a friend and I gifted 3 games to our mates, plus 2-3 more bought the game just to join in. Then this night time only thing was their 1st impression of this game. They are ALL new to the game, none of them played the mod before. Please hurry I don't want to loose their interest before they even get started!
As a side note - I don't mind the dark, just consider adding additional types of light sources, example a lantern to put on a table inside a house or to carry that has a different kind of unfocused, circular light that lights up an area whereas the flashlight remains as it is... focused. Also consider items that can be powered by alternative power source such as solar power or hand cranking action LOL keep up the good work.