Oof, that sounds nasty. Did it turn out to be a standard-ish formatting with a separator where you break the line after x number of separators? I really dislike having to parse a log like that before just being able to read the log

From memory there was no dedicated event separator, it just went straight from the last character of the event to the first character of the timestamp of the next event. I think there was an XML payload in the event somewhere too?

Fortunately I didn't have to edit the log in-place as we were ingesting it into Splunk, so I just wrote some parsing configuration and Splunk was able to munch on it without issue.