Participants register to attend the Google Calendar event via Google Form
Select slot's custom format then copy/paste one of patterns from the table at the end of this page
Find the time code HH:mm
Replace with this hh:mm a
Save the add-on and test a submission
That's all
${"Event title"} | ${"Start M/d/yyyy',' hh:mm a"} - ${"End hh:mm a"} * ${"Event location"} (${"Accepted guests"}/${"Invited guests"}/${"Guests limit"})
You can try your own format with different Date and Time Patterns