Did you take a look at the SYS.ApplicationError class? It has methods and class queries for reading the Application Error Log.

For example, to get the dates when errors were logged for a particular namespace TEST, you can use

do ##class(%ResultSet).RunQuery("SYS.ApplicationError", "DateList", "TEST")  

Or to manually parse the results, you can use

set resultSet = ##class(%Library.ResultSet).%New("SYS.ApplicationError:DateList")
set status = resultSet.%Execute("TEST")