Just to clarify, the list of items in the third pane when using the Menu Bar Items... action is not stored in the catalogue. It is generated on the fly when the action is used. So that's why Rob pointed this out to you, Berry.
If you want to make a permanent trigger for a menu bar item, paste the following line of text (with the necessary changes so that it refers to the menu item you want) into the first pane of your trigger, and then select the Run as AppleScript action in the second pane.
tell application "System Events" to tell application process "Finder" to click menu item "New Finder Window" of menu 1 of menu bar item "File" of menu bar 1
The above will get you to the menu items in the first level of the menu. If you want to click a nested menu item (e.g. View > Sort By > Snap to Grid), use this form:
tell application "System Events" to tell application process "Finder" to click menu item "Snap to Grid" of menu 1 of menu item "Sort By" of menu 1 of menu bar item "View" of menu bar 1