Does this look good or not ? (night window rays)

[TheGreatCthulhu]

They can be realistic - rays are just light reflecting from the dust particles floating in the air, although the moonlight is a lot less strong compared to the daytime sunlight. If the room is dark enough, and the Moon is very bright, it should be possible to see subtle light rays.

Another point - the direction: light comes from the direction of the Moon, so it cannot be at an angle. If you imagine a straight line going from the center of the window to the light source (the Moon), that line defines the general direction of the rays. So either reposition the moon or rotate the rays.

Finally, the next suggestion is a matter of preference, I think you should make the rays really subtle, almost barely visible. Often, what looks good on a still image, looks a bit too strong in an animation or in a virtual environment where you can move around.