Strategy when creation date or tag is not correct

I have a lot of scanned photos from the analog age. From most I changed the creation date and tags with the exiftool. But when I did an import in FS I saw that I forgot some photos/videos to change the creation date or the tags were wrong.

I changed the creation date in the original and did a resync of the asset in FS. Now I have the photo with the old date and a photo with the new date in FS. I did not change the wrong tags yet.

Basically my question is what is the strategy to change for instance the creation date or a tag when an asset is already imported in FS?
Where should I edit something, is a resync of the asset sufficient, do I need to delete something manually, should I wait for the new version?

Scanned images are pesky: I have boxes of undated prints and negatives, and most aren’t dated: that’s a task I haven’t tackled yet.

Edit: more details for this issue is here: