Attached is the patch to fix the RM #3029 Cannot sort columns when importing data.
Select2 orders the selections based on the order of the `<options>` behind the scenes. This means that the order will typically match the order of the options as they appear in the dropdown. For import/export it shows in the order of columns define in the table.
Solution: I have just reorders the options inside the select2 every time, an item is selected. I have made this change into the select2 control with new option "preserveSelectionOrder" by default it is false, so won't impact any other module.