I have noticed that log printout for this setting is missing a space between fixed text and user defined label.
If I set in knime-server.config file com.knime.server.webportal.title_label=SERVER NAME, log will print out:
com.knime.[sic].ServerConfigImpl readWebportalTitle: Setting WebPortal title toSERVER NAME
This can be clealy seen in com.knime.enterprise.server.config.ServerConfigImpl.java file in readWebportalTitle(...).