There should be a Shared Parameters Search Box on both the 'Shared Parameters' and'Edit Shared Parameters' menu, just above the Parameter Group drop down menu.
At the present moment not having the option to search for Parameters in the Shared Parameter File leads to a lot of duplication and the creation of similar parameters. This leads to disparity between your Revit Templates, Schedules and Family Library, and fixing them is a tedious and expensive task.
Having a Search Box will also greatly reduce the time you spend on searching for the right Parameter.
Introducing a simple Search Box to the Shared Parameters menu can greatly improve our Revit Experience and save us a lot of frustration, time and money.