None of the events show the average rating:
https://musicbrainz.org/artist/9252ca18-015c-484c-ae59-5670784887d3/events

But there are plenty and the average is currently shown with 5 stars:
https://musicbrainz.org/event/73662470-40ef-4fcf-bbd7-2646a0ca3183/ratings

Place ratings are affected as well:
https://musicbrainz.org/place/73fdfed7-2549-4041-b940-2752ea1afed2/events
https://musicbrainz.org/event/52c3bf63-66f2-4042-b1c6-5724306b0630/ratings