Hello, I’m one of the developers behind the plugin Storyteller.
Thank you for your interest, you can of course use the plugin for your own NPCs.
As for your issue, we released a second version where the command doesn’t cause an exception anymore. It now works properly.
We are aware that the configuration is not very user friendly, and we are open to any suggestion to reduce its sensitivity - we are otherwise working on a tool able to generate the config from a web UI, that should help people to use the plugin without being bored with too much syntax.