It is not necessary to manually edit each named symbology. The Global Name Symbology edit command which will allow you to change all occurrences of a particular value in the XIN file was added to InRoads V08.07 and above. This command is an Application Add-in, Named Symbology Tools and is not available when running AutoCAD.
One thing you can't globally edit are symbology names. Export to CSV, edit , then import to accomplish this.