As the SPAD.neXt VoiceAttack plugin is strictly based around "set" and "get" instructions, it doesn't actually keep track of any values, it just sends instructions to the SPAD.neXt application. So there's no real way to have an event based system within VoiceAttack triggering off the plugin, as there isn't any data to go on.
You'd have to ask "Ulrich" to implement command triggering into SPAD.neXt, as plugins can trigger commands, but they have to be setup specifically to do so from within the plugin itself.
You could create a single command that monitors for these changes and executes relevant commands, E.G.
Set Boolean [DayNightPrev] to [DayNight]
Start Loop While : [{EXP:1=1}] Equals '1'
Begin Boolean Compare : [DayNight] Does Not Equal [DayNightPrev]
Execute command, 'Toggle lights' (and wait until it completes)
Set Boolean [DayNightPrev] to [DayNight]
End Condition
End Loop
But you still have to query SPAD.neXt for the data every time, there's no getting around that.