Take a look at the Numara.TrackIt.Core.Search.SERVICE.xml in this directory:
C:\Program Files\Numara Software\Numara Track-It!\Track-It! Services\ConfigurationData
In that file, there are lists of columns that the search feature looks at in the various modules (Inventory, Help Desk, etc.). You could add more database column names but if the columns don't have an index in the database it could cause some pretty poor search performance. If you do decide to make any changes to the file you'll need to make sure you delete all of the existing files under the ..\SearchData folder:
C:\Program Files\Numara Software\Numara Track-It!\Track-It! Services\SearchData
And then restart the Track-It! Service Management service.
Yes. That particular line you are referring to (WORKSTAT) has to do with the Inventory module searches. For work orders, the line contains TASKS.
<TASKS primaryKey="WOID" columns="REQUEST,PHONE,EMAILADDR...
The column names are the actual names of the columns in the TASKS table. They may or may not be self explanatory on what fields in the application they refer to.