OP here. Unless you work for a certificate authority or a web browser, this event will have zero impact on you. While this particular CT log has failed, there are many other CT logs, and certificates are required to be logged to 2-3 different logs (depending on certificate lifetime) so that if a log fails web browsers can rely on one of the other logs to ensure the certificate is publicly logged.

This is the 8th log to fail (although the first caused by a bit flip), and log failure has never caused a user-facing certificate error. The overall CT ecosystem has proven very resilient, even if a bit flip can take out an individual log.

(P.S. No one knows if it was really a cosmic ray or not. But it's almost certainly a random hardware error rather than a software bug, and cosmic ray is just the informal term people like to use for unexplained hardware bit flips.)