This is the code that I am using and it is not changing the alignments on the text symbol position properties.
string mapTitle = "Notification Labels" + prjName + "Buffer: " + SizeUnits;
Coordinate2D titleTxt_ll = new Coordinate2D(2.9538, 9.9116);
CIMTextSymbol arial18bold = SymbolFactory.Instance.ConstructTextSymbol(ColorFactory.Instance.BlackRGB, 18, "Arial", "Bold");
arial18bold.HorizontalAlignment = ArcGIS.Core.CIM.HorizontalAlignment.Center;
arial18bold.VerticalAlignment = ArcGIS.Core.CIM.VerticalAlignment.Top;
GraphicElement titleTxtElm = LayoutElementFactory.Instance.CreatePointTextGraphicElement(newLayout, titleTxt_ll, mapTitle, arial18bold);
titleTxtElm.SetName("Title Text");