There are no client errors for that schema reported in Grafana:
https://grafana.wikimedia.org/d/000000018/eventlogging-schema?orgId=1&var-schema=ElementTiming
No eventlogging_EventError in logstash either for that schema. I also looked at raw events that contain ruwiki (the only wiki these events are coming from), but all the errors were for other schemas.
Where are these events going?