Reply To: Flippable Annual Report Setup

If this is being printed first talk to your printer.

I would create this as two files of the same number of pages and have the printer impose it to suit.
This would be two standard documents it will be easy enough to work on, just open the two documents side by side as if it were a spread.

I would make this a Book file so that your paragraph styles etc are synced between the documents and even have styles based on each other one for English and one for French so that the language is set correctly for each section.

If the printer insists on a single file you could create a PDF file and move and rotate the pages as required by the printer.