You can hide the log message for a specific command by adding the "Ignore an Unrecognized Word or Phrase" action to it, which doesn't actually affect the command in any way aside from getting rid of the initial execution log message (the "Write a Value to the Event Log" action and other log output from that command will still work).
Note that the action is not affected by the flow of the command; Regardless of where it is in your action list, it will function (only disabling the action will stop it from doing so).