macfrombrampton wrote:
that site you provided is on how to configure and use the firewall. i did not ask for that information.
You asked Why is there no Firewall logs in High sierra which cannot be answered because it is a false assertion. Firewall logging has been improved and needs to be enabled and configured for whatever specific purpose you require.
Logging in macOS Sierra and HS is explained in man log. For help regarding the application firewall specifically, use /usr/libexec/ApplicationFirewall/socketfilterfw -h
Firewall logging options are set with --setloggingopt
In addition to being much more efficient it provides far greater detail than was available in previous macOS versions.