Where is your event chronicle located? Based on your description it sounds like the Pro+, because PHV can enumerate all known event chronicles. If you look in DeltaV explorer under the Alarms and Events field of each workstation or application station node, you can see which are enabled as event chronicles. If there are more enabled than you can see in the PHV list, then the chronicles may not have been downloaded and are not working.
Obviously, localhost will only work if the workstation where you launch PHV is also a chronicle.
Defaulthost is tricky. It represents what you as a user has selected for the client workstation as your default chronicle. The default chronicle is used for event charts by default. It is user-profile based, and could potentially vary for each user on each workstation. The "default" default chronicle is localhost, I believe.
Now for testing, lets do the following:
1. **Non-Admin** user should log in to Windows and DeltaV on a workstation.
2. Open PHV and select File-->Set Default Data Servers
3. Under Event Chronicle, Select Pro+ for the Events Data Server. Ensure 'save as my Application Startup Data Server' is checked.
4. Open a new Event file, File-->New-->Event.
5. Select Events-->Configure Events.
6. In the Configure Event Chronicle dialog, see if the Events drop down contains any current datasets.
If you don't see current data sets, repeat this process for the admin user. If he DOES see extra chronicles, then as I said, it would seem to be a permissions issue on the current data sets in SQL.