In PI System Explorer, we only provide UI guidance (Intellisense) for the element attributes when configuring the analyses and that is by design. We purposefully do not provide UI guidance for child attributes as that would require us to load into the client UI all the attributes and child attributes for that element. This would negatively impact client performance and would exhaust the resources on the client machine easily.
Alternatively, you can go to the attributes pane to select child attributes in PI System Explorer and either drag and drop or “insert” attributes from all levels into the analysis configuration.