Payara Server & Logging

I am currently trying to get payara to log to our graylog server. It works fine when logging to syslog and then using that to forward to graylog. I however have 2 problems with that:

  1. the host is set as localhost.localdomain
  2. i cannot see which node and application is writing the log

the first one can be worked around according to an issue i found on SO (rsyslog - send payara logs to graylog via syslog and set correct source - Stack Overflow) but i struggle with the second one.
I had multiple ideas, but the general problem seems to be that there is a fixed layout for the logging messages. I also cannot switch the message to json to make it easily parsable.
Is there any possiblity to tweak the syslog output and add extra fields, preferably without changing the applications themselves.