Private Sub Worksheet_Change(ByVal Target As Range)
    Dim Eingabe As Variant
    On Error GoTo fehler1
    
    With Target
        If Not Intersect(Target, Range("C2,H2,F37,F43,C5:E35")) Is Nothing Then
            Application.EnableEvents = False
            If IsEmpty(Target) Then GoTo fehler1
            
            If Not Intersect(Target, Range("C5:C35,F47")) Is Nothing Then
               If Not IsNumeric(.Value) Then
                   .Value = WorksheetFunction.Proper(.Value)
               Else
                    If Len(.Value) = 5 Then
                        .Value = Left(Format(Target, "00000"), 3) & ":" & Right(Target, 2)
                        .NumberFormat = "[hh]:mm"
                    End If
               End If
               GoTo fehler1
            End If
            
            If Not IsNumeric(.Value) Then GoTo fehler1
     
            If Len(.Value) = 4 Then
                .Value = Left(Format(Target, "0000"), 2) & ":" & Right(Target, 2)
                .NumberFormat = "[hh]:mm"
            End If
           
        End If
    End With
End If

fehler1:
Application.EnableEvents = True
End Sub