I've created a few custom Curtain Walls and I believe the required Catalogs and Cells are in the right locations within my Update 7 workspace. However, my custom versions do not display in the available list during placement, and when using Catalog Editor these custom Curtain Wall catalog items cannot find my customized MullionProfiles.cel library.
In our delivered datasets we include the files CurtainWall_Frames.xml, CurtainWall_Panels.xml and CurtainWall_Systems.xml, each containing catalog items for placement of that specific Curtain Wall sub-component.
The user in this case had three files of the same name but that included their customizations. When adding new catalog items for any existing catalog type, the "safest" method is to choose the closest existing catalog item, use the right-click Duplicate command, and then change the applicable properties as needed for the duplicated item as described for Walls in this wiki.
In this example I've duplicated the Curtain Wall Frame as shown below. Simply repeat the same process for the Panel and System so that you have a matching set.
Next, in the Catalog Editor choose your new Frame and Panel in the respective drop-downs for the new Curtain Wall System. Once that is in place, you should see your new Curtain Wall in the placement dialog with the custom Frame and Panels as shown:
Lastly, it is best to rename your custom cell library so it doesn't conflict with delivered MullionProfiles.cel file, and place that library in the applicable workset's \cell folder. You should now be able to choose your customized cell for your custom frame object as shown here:
After placing an instance of your custom Curtain Wall System you can verify the changes have taken effect by measuring it vs. an existing and/or delivered version.