In order for custom visualizations to be available throughout Splunk, you have to set visibility/permissions to "global". In order to do this, select "Permissions" in the App Management menu and change the permissions to "All apps"
Alternatively, there is a standalone app, provided by a member of the Splunk community, which has more features than the one included in the Dashboard Examples app: https://splunkbase.splunk.com/app/3212/
Hi, did you have to change any references in the config files of the tagcloud visualization? after adding it to your own app?