update_login_failed_count should, if I read this correctly, write a log message for the plugin Simple History whenever a lockout is put in place.

However, I was just unable to login on a website on a new computer (with a message informing me about a lockout in place) without there being any message in the Simple History logs (they only were about the global lock counter increased for attempts to log in using an account admin that does not exist).

Sadly, I currently don't have further details about this issue (other than having experienced it occasionally for several months in a row now). I am in the process of collecting more evidence, which I will upload here as soon as I find some :)