My Trello Backup Script just got a whole lot more flexible.
Some of the old custom fields that aren't found in the Trello API are still available (e.g. Story Points or Cost extracted from the card title), but if you don't want them, just delete them.
Because of these changes, it was necessary to change the way that the story card generation worked, since the column order was no longer guaranteed. Instead, you now put the column heading in the cell where you want it to appear in the card template spreadsheet, wrapping it in $'s. e.g. to output the Acceptance Criteria, you simply put $acceptance criteria$ in the cell where you want it to go.