populate list with each new value

This will find your value in the list, you will have to work from there

Private Sub Worksheet_Change(ByVal Target As Range)
Dim where As Range, where1 As Range, rng As Range, Vsl As String, lr as Long

If Target.Column = 2 Then

Vsl = Target.Value

With ThisWorkbook.Worksheets("Parameters")
lr = .Range("e" & Rows.Count).End(xlUp).Row
Set rng = .Range("E2:E" & lr)
Set where1 = rng.Find(Vsl, LookIn:=xlValues)

        
    If where1 Is Nothing Then
        .Range("E" & lr + 1).Value = Vsl
        .Range("e1", .Range("e1").End(xlDown)).Sort Key1:=.Range("e1"), Order1:=xlAscending
    End If
        
    End With
End If

End Sub

Remove all code from the Sheet modules and try this one in ThisWorkbook module.

Also I would make your Vsl range a dynamic one to avoid all the empty rows at the bottom.

Private Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range)
    If Target.Column <> 2 Then Exit Sub
    If Target.Value = vbNullString Then Exit Sub
    If Sh.Name <> "Parameters" Then
        fRow = Application.Match(Target.Value, Sheets("Parameters").Columns(5), 0)
        If IsError(fRow) Then
            With Sheets("Parameters")
                .Range("E" & .Rows.Count).End(xlUp).Offset(1) = Target.Value
                .Range("E2", .Range("E" & .Rows.Count).End(xlUp)).Sort .Range("E2"), xlAscending
            End With
        End If
    End If
End Sub

In ThisWorkbook module.

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

    If Target.Column <> 2 Then Exit Sub
    If Target.Value = vbNullString Then Exit Sub

    If Evaluate("count(search({""H&M"",""CREW HEALTH"",""A&I P&I""},""" & Sh.Name & """))=1") Then
        fRow = Application.Match(Target.Value, Sheets("Parameters").Columns(5), 0)
        If IsError(fRow) Then
            With Sheets("Parameters")
                .Range("E" & .Rows.Count).End(xlUp).Offset(1) = Target.Value
                .Range("E2", .Range("E" & .Rows.Count).End(xlUp)).Sort .Range("E2"), xlAscending
            End With
        End If
    End If
    
End Sub

Fontcolor was a remainder of earlier attempts , just had to put entire column E back to Automatic.

Changed your Datavalidation to a Dynamic Range to avoid empty rows at the bottom.(only1 now to allow new entries)

You're welcome.

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