Is there a good syslog viewer for mac?
At last, one developer is making both tools you seek.

Howard Oakley has beta versions of his programs at https://eclecticlight.co/downloads/ and blogs regularly about how to use these and explore the new log archive formats on macOS / iOS / tvOS / watchOS

His downloads page has two apps of interest (use the left downloads link as the product versions below are beta and may not be current in a day or week):


Consolation - an alternative console browser
Woodpile - a tool to count / bin / analyze patterns of logging


If you picked one blog post of his to look at regarding logging, I would start here:


https://eclecticlight.co/2017/11/22/the-unified-log-in-high-sierra-10-13-1/