Hi Robert,
There is no way to access Data Generator from script. Do you see any other applications of this functionality, except for the task you mentioned? I am asking this, because I can register this request, but we need to understand exactly what the functionality is needed for.
As for now, it is possible to solve such a problem by exporting the generated data to an Excel file. You will be able to edit columns by means of Excel. I have registered your request to have the ability to re-generate column data by using the Data Generator Wizard.