The crpg time, which governs the battle time is understandable because it allows you to compare server time to your local time and get them in sync.
The strat night time display is AFU and confusing. For example, mine now says GMT -3. But I'm in GMT -4.
Much more sensible would be to specify what time GMT that you wanted night time to start. Then it would be easy to set what local time you wanted night time to start. If you were GMT -7 and you wanted night to start at 2300 local time, you would input 0600 GMT as the start of night time (0600-7=2300).
Right now my strat night time is set at 00:00 GMT -3. I'm assuming (always dangerous) that that means 2300 in GMT -4 time zone.