This solution should work: https://jsfiddle.net/handsoncode/k39a7Ljd/ It will update the source data after the columns movement so when you export the table to CSV file after moving the column you should now get the updated formula.
That would be more complicated as it turns out that HyperFormula save the reformatted formula into the source data, but Handsontable doesn’t do the same, but there’s a reason for this. As while me move the columns only the visual layer of the data is being modified, and the source data stays intact. That’s a a design choice, and to save the visual data to the source with correct column reindexing would require more customization. We don’t have any guides or examples for such scenario, but if you decide to implement this solution you might need to use the indexMapper: https://handsontable.com/docs/react-data-grid/api/index-mapper/ and hooks and methods like listed below: