To reproduce: 

CultureInfo cultureInfo = new CultureInfo("es-ES");
var currency_info = new Telerik.Windows.Documents.Spreadsheet.Formatting.FormatStrings.CurrencyInfo(cultureInfo.NumberFormat.CurrencySymbol, cultureInfo);
var format_string = AccountingFormatStringBuilder.BuildFormatString(currency_info, cultureInfo.NumberFormat.CurrencyDecimalDigits);