In that case it looks like a permissions issue. If you want to use these aliases inside search, change the permissions for the aliases in local.meta so that they're exported system wide for read. And also any other objects inside the app that you might want to use from another app.
I haven't loaded this app since I don't have a fortigate, but typically an installation will set the knowledge objects to be only visible within the originating app.
Make sure, of course, that any objects you do this to, don't conflict with things exported from other apps (unlikely, as they should be tied to sourcetypes only applicable to fortigate, but worth checking nonetheless), or you won't get the results you expect. You can use btool to check the work.
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