Sometimes you have to map a LOT of columns from one table to another and create a really big JSON template.
I had to do a table with over 100 columns, so I built a template generator to provide a dropdown menu of columns and add all the extra characters.
Just paste in your two rows of column headers, and use the dropdown to finish generating your template.
The sheet is public, but view-only. Copy the template to your GDrive to use.