All of the events in LAi_Fightparams.c are hardcoded into the engine and are part of the NPC character init when they are instantiated, for the engine to gather values that can be set from the scripts, as part of the character's AI settings.
You can define your own events, but unless you want a time delay, it's just as easy to directly call the function that the event would call as part of the handler. And your user-defined events can only be called from some other part of the script code execution defined by you, and won't be launched by the engine on its own, like these hardcoded events.