Hi,
The databases under the ServerLog schema are mainly for archiving/logging purposes. It stores past and current information about every stages of your workflow. It is not the actual working space your process instance will use.
Having said that, that post you just linked is created back in 2014. There are a lot of changes made between 2014 and 2019. For example, older versions of K2 uses a 14 databases, while later versions uses 1 single consolidated database with multiple schemas. I do not see ServerLog.Error in my database as well.
There is however a Server.ErrorLog table and Server.ErrorProfile table. Both simply stores the error your current process instance is getting, and you can actually view the error message over on your Management page.