Steps to reproduce:
1) Add RadGridView control
2) Use GridViewDecimalColumn:

        DataTable customDataTable = new DataTable();
        sampleDataTable.Columns.Add("Column name", typeof(double));

3) Set the right-to-left property of the control to true:

        this.radGridView1.RightToLeft = System.Windows.Forms.RightToLeft.Yes;

4) Set the following CellElement properties using CellFormatting event:

        void radGridView1_CellFormatting(object sender, Telerik.WinControls.UI.CellFormattingEventArgs e)
        {
            if (e.CellElement is GridDataCellElement)
            {
                e.CellElement.RightToLeft = false;
            }
        }

5) Re-size the form manually until the horizontal scroll-bar disappears
6) Resize a GridHeaderCellElement in left direction and you will notice that the GridDataCellElements from this columns are resized to the right direction

Whenever I'm trying to expand any column the header expands as expected but the column itself is expanding in the other direction so the headers and columns content are not aligned. 
Expected result: expand the column content properly
Actual result: the GridDataCellElements from this columns are expanding incorrectly