EPPlus support for sheet right to left alignment

worksheet.View.RightToLeft = true;

I think you want to set the View object of the worksheet:

using (var package = new ExcelPackage(fileinfo))
{
    var workbook = package.Workbook;
    var worksheet = workbook.Worksheets.Add("RightToLeft");

    //Set the worksheet right-to-left
    worksheet.View.RightToLeft = true;

    package.Save();
}