One XLSX file with a sheet for each kind of data: farm, members, boxes, occupied cells, plants, log, measurements, solutions, solutions in boxes, custom varieties, custom box types.
Times in the file are the farm's local time.
IDs and codes are in separate columns from names: a status, action or reason code is the same in any interface language, while column and variety names follow the language chosen in the product.
Members' phone numbers and notes are included only when the owner exports. An administrator gets these columns empty - the same way they see the member list.