Fantastical Siri shortcut entry from initial voice input?

I’m setting up a Siri shortcut to enter events into Fantastical by voice. I’d like to use its “create event or task from input” method. However, I can’t find a way to do it in one line, i.e., to have a shortcut named “input new event” create an event from “input new event review documents 11am.”

If I just say “input new event,” Siri will ask me for the input string and Fantastical will handle it correctly. If I say the whole line, then it will be sent to the Calendar app or Reminders app if the shortcut name sounds like something one of them can handle, or else Siri will ask which app or say it didn’t understand the string.

Is there a way to set this up and get the behavior I want? I asked Fantastical support but they don’t do any support for Siri entry.

The reason I want Fantastical to parse is because it adds to specific calendars by voice, and because the native Calendar app detects conflicts from calendars which are hidden in Fantastical.