Currently auto complete has a few of issues:
1. It does not obey org boundaries
2. If the user only has access to a few items dues to his roles, auto complete will suggest ones he does not have access to.
3. Controller Rules were not added for the auto complete action, so it does not currently work in most of the controllers.
The issues raised in the initial description were addressed; however, the project recently moved to a search solution involving a full-text search engine. With that move, support for auto-complete on search values is no longer supported. If required/needed in the future, we can introduce and RFE/feature/story to support with the new search engine.