That's an interesting question? It also appears to be correct too, you can't see a resource imported by someone else unless they share it.
Here's a potential solution though. Create a dynamic resource group that would include the imported resources and share this to all of your administrators. Then no matter who imports the object they will be visible to all of your administrators.
Another solution might well be that you don't allow any one but a designated person to import resources.
I tested the scenario above and it works but if you let everyone do auto discovery managing ownership of the objects is going to be a nightmare! The administrators will all own parts of your estate and their view of resources will all be different. If you manage import centrally this problem goes away, they all have a single view.
You could also make them super administrators - they can see everything but that's a pretty powerful role and if you are allowing teams to manage passwords separately then it will break those Chinese walls. Auditing password access will assist you here but not really plug the security hole.