Letter of the Week Displayed on a card based on Google Calendar Events

Long story short, I’m working on a custom display for my 4 year old daughter. I am currently displaying her light switch, how many stars she has (Thank you KidsChores Add on), and a custom code I set up to display a shining sun if its “time to be awake” and a crescent moon if its “time to be asleep.”
What I would like to add to this is a card that will display the current letter of the week at her school. I would look at my calendar events and search for “letter of the week” (non case sensitive) and display the event that happened most recently. The calendar starts the week with the new letter on Sunday, son on Sunday the card would update to the new letter.
I’ve attempted to filter calendar events using Atomic Calendar Revive. While I can get it to populate the events, the filtering does not seem to work at all. All upcoming events are displayed.
Is this an issue with my configuration? or is there a different add on I could try to accomplish this goal?

type: custom:atomic-calendar-revive
name: Letter of the Week
entities:
  - entity: calendar.xxxxxxx
eventFilter: (?i)^letter of the week
filterMode: include
filterProperty: description
maxDaysToShow: 7
showLoader: true
showCurrentEventLine: false
showDate: true
showDeclined: false
showNoEventsForToday: true
showEventIcon: true
hideFinishedEvents: true
sortBy: start```