The odd thing is that "Night" is currently a tick box separate to the other field (where you choose between sprint, middle, long, relay, cross country, urban, score, trail-O and closed event)
Night is correctly separated out as it is independent of the other choices.
In effect the (unpublished) default is day, although you could argue that some events such as the Harvester need a third day/night option. Having said that, it does sound as though if collected it would be useful if it was used somewhere.
There are course types (eg score, cross - country, relay) and event types (eg. night, urban, mountain bike).
I find this then gets confusing.
The choices come from:
How is it done - on foot, on a bike, on skis
What sort of race is it - take the controls in order (usually referred to as cross country which isn't a good name for it as you can have a cross country urban event), score, trail O, and there may be more
What sort of race is it - individual, relay, team
What length of event - long O, normal, middle, sprint
What type of terrain - traditional or urban
This would lead to a few more boxes, but with the benefit of a much better description of the type of event. For example someone could stage and advertise a bike score event around the streets at night. Good fun, but not sure about the risk assessment.