Unfortunately the Shortcuts app can't talk to the Google Calendar app yet, which means that for other Siri shortcuts to have access to your plans to use the data for stuff, you need to add those items manually. And then you need to add them again to Google Calendar manually. This shortcut is designed to speed you through that as much as possible.
I did a lot of work to figure out how to pass the details of this event to the Set Alarms shortcut, but then I realized that because alarms don't have a "date" property, they can only be set for today's date. And usually calendar events are set up before that day. Oh well! The functionality is still there if you need it.
Here are some of the ways this shortcut makes calendar entry easier:
Hopefully these improvements make it easier to add calendar events more consistently.