Use RTF text for header & footer text

FastReport allow only tags for bold, underline & italics in HTML tags.

    <RichObject Name="to_sale_order_eq_head_text" Left="56.7" Top="18.9" Width="663.39" Height="20.06" IsIntersectedWithOtherObject="true" CanGrow="true" CanShrink="false" Text="[sale_order.eq_head_text]" Font="Arial, 8pt" TextRenderType="HtmlTags"/>

Replace also

  to_sale_order_eq_head_text.Text = EqFastReportCoreFunctions.EqCoreFunctions.ConvertHTMLToRTF((String)Report.GetColumnValue(&quot;sale_order.eq_head_text&quot;), txtRTF.Font.Name, ((decimal)txtRTF.Font.Size));