Correct Google Photos Export Metadata -- 2

I’ve downloaded my full library from Google Photos through Google Takeout and discovered that the embedded metadata is a mess—both the timestamps and the GPS coordinates are wrong for every photo and video. The correct information is still available in the accompanying *.json sidecar files that Google provides, yet it never made it into the actual files themselves.

What I need
• A reliable way to inject the right “Date Taken / Creation Time” and latitude-longitude values into the EXIF of each JPEG and the corresponding metadata tracks of each MP4/MOV.
• The process must work in bulk, not file-by-file; I have thousands of items.
• The end result should be either (a) a cleaned, ready-to-archive copy of all media with accurate metadata or (b) a repeatable script/tool (ExifTool, FFmpeg, Python, etc.) plus clear instructions so I can run it myself on future exports.

Acceptance criteria
1. After processing, the macOS Finder, Windows Explorer, Google Photos re-imports, and Lightroom all show the corrected date, time, and location without manual intervention.
2. No visual quality loss in photos or videos.
3. Original files are preserved in a separate folder; only duplicates are modified.

If you’ve handled Google Takeout libraries before or are comfortable scripting ExifTool/FFmpeg to merge JSON data, I’d love to get this wrapped up quickly.