Mixed case requirements in same cell!

Why not do aText to Columns so the code does its job correctly on the surnames. As initials are isolated use a function to convert them to uppercase. Then concatenate the results.

Hello Spellbound,

I am not sure if I have placed the call to the macro in the correct place in your macro. It is in blue to make it easy see and change it if you need to.

Macro to convert characters in parentheses to upper case
Copy this code into a Standard VBA module.

Sub Macro1(ByRef Rng As Range)

  Dim Cell As Range
  Dim Matches As Object
  Dim RE As Object
  
    Set RE = CreateObject("VBScript.RegExp")
    RE.Global = False
    RE.Pattern = "\(\w+\)"
      
     'Find the first group of characters in parentheses and make them upper case
      For Each Cell In Rng.Cells
        Set Matches = RE.Execute(Cell)
        If Matches.Count > 0 Then
           Cell = RE.Replace(Cells, UCase(Matches(0)))
        End If
      Next Cell

    Set RE = Nothing
    Set Matches = Nothing
  
End Sub

Your Macro with the change

Private Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range)
    Dim cell  As Range

    Application.EnableEvents = False
    
    Select Case Sh.CodeName
        Case "Sheet4"
            For Each cell In Target.Cells
                Select Case cell.Column
                    Case 3, 4, 6, 8, 9, 13, 15, 16
                        If Case = 4 Then Call Macro1(Target)
                        cell.Value = StrConv(cell.Text, vbProperCase)
                    Case 10, 17
                        cell.Value = StrConv(cell.Text, vbUpperCase)
                End Select
            Next cell

        Case "Input1"
            For Each cell In Target.Cells
                Select Case cell.Column
                    Case 5, 13
                        cell.Value = StrConv(cell.Text, vbUpperCase)
                End Select
            Next cell

        Case "Sheet7"
            For Each cell In Target.Cells
                Select Case cell.Column
                    Case 3, 6
                        cell.Value = StrConv(cell.Text, vbUpperCase)
                End Select
            Next cell
        End Select
    Application.EnableEvents = True

End Sub

Hello Spellbound,

The Target is passed into the Workbook_SheetChange event ByVal. The new macro takes the Range ByRef. Change the offending line of code to this...

If Case = 4 Then Call Macro1(Sheets(Sh.CodeName).Range(Target.Address))