The first thing I would check in the Sage Export Sales Journal  is if the Column# on the Export for the fields "Description" and "GL" are the same column# in the Import Sales Journal.  If not, make them the same.  Also I should mention the Customer Name is not checked in the field settings ,show column for both the export and import, so if you want the customer name to not be blank, check the show box for both export and import.  You might want to save both the export and import as a User defined Template.

Go to your options tab > global settings.  Uncheck hide gl accounts on sales invioces and and any other place you want it unhidden.   Also go to the second tab and give yourself 2 line display.  I think you will like it.

On the Sales Invoice screen choose Layout from the menu. Choose Predefined Product. This should show the Gl and description that was imported