>>3148959800 ISO is just one stop more light or faster shutter speed than regular daylight 400 ISO, you won't magically be able to shoot at night if there are no strong lights around.
For reference, this is the best night shot I've been able to get with Cinestill 800T exposed at EI 800: a grainy mess where everything not under direct light is almost pitch black, and afaik 1600 film doesn't make it much better.
