System module not logging severity & facility

Judging from the ingest pipeline definition of the Filebeat system module, it currently does not support logging of the severity and facility of an event, even if you adapt your syslog daemon configuration to log these in the log file.

Being able to filter on events greater than a certain severity level is obviously a very useful feature for central logging. Is there any way to get this to work currently, or are there any plans in the near future to support this?