Suppose you manually (i.e. using notepad) add a logging formatter to a WildFly config:
The next time you start WildFly, it propagates this change into logging.properties.
Now stop WildFly and change "bar" to something else. Then start WildFly again. You will notice that your change is not propagated into logging.properties, and therefore never takes effect. Changing a property name also does not work. Neither does adding more properties. Neither does removing properties, except when you remove all of them.