I wasn't able to catch spawned characters in Story scripts either, which is why I focused everything around the spawning character (original character). The spawned enemies don't trigger CharacterDied events at the very least.
The reason charScripts might work over Story scripts is due to either the spawned character using a charScript themselves or because it matters more for AI in combat since it allows them to be targetted.
Yeh sadly there is no way I can think of (and I tried many

) to catch them in story scripts. It would be great though to create and manipulate characters on the fly, like for some RTS element that I'm working on in my own mod. Will shelf that idea sadly.
edit: when I create a character template and then remove the original template from the game(ie destroychar), the new character is recognised by story scripting as if it where the original one.