Before-and-after JSON-to-CSV review: compare values by key

To review a JSON-to-CSV change, map each CSV row back to a source record using a stable key. Compare selected fields, null handling, nested-value representation, and column order. Do not rely on row position alone if the converter can reorder records. Check quoted commas, newlines, and Unicode. If the spreadsheet displays a number differently, inspect the raw CSV to distinguish export behavior from viewer formatting. Record any intentional loss of type information.