Incorrect facial recognition in Photos

You are right, that Photos can make mistakes when recognizing faces. You can improve the performance by helping Photos to learn what a person looks like.

Photos is trying to learn what a person looks like by using the labeled faces for a person.

It is important to catch classification errors early, before Photos is using incorrectly named faces to learn.

I am always checking what the face recognition is doing. When I get an alert, like "You confirmed 3 faces and 10 faces have been added automatically" I open the album for the person and check each face and correct any mistakes immediately. Or the error may propagate. Now, that I have several hundred correctly labeled photos in many people albums, there are less and less classification errors. But Photos is still occasionally mixing up the faces of close relatives, but only in in photos, where I could not tell them apart either, if I would just look at the face.

are you saying one would ONLY find out if you happened, accidentally, to open the album of that person?

Not accidentally. You have to take control over what Photos is learning. If you allow Photos to keep misidentified faces in a Persons album, you will have lost, because Photos may add more and more incorrectly identified faces to that album,

a) have faces that are not recognised as faces,

We can only hope that Photos will get improved. I am having plenty of similar photos , mostly old family scans, that are having a very small pixel size, where I have to add the faces manually. At least we can add missing faces manually on a Mac. This is not possible at all in Photos on an iPad or iPhone.

b) faces WITHOUT a name

Thy might be added, if you use "Confirm additional faces" for the album of that person, if that person exists in your library. usually I am glad that Photos did not add a name by its own, because naming automatically would be causing the mixed persons.

c) Faces that will NEVER be identified which cannot have the 'circle' removed!

That is the worst - I have thousands of photos of strangers in the background or some artifacts that clutter up the faces labels.

This new feature has been around since macOS 10.13 High Sierra. We are no longer allowed to remove automatically identified faces, even if they are no face at all.

I also hate this "Updating..........XXXXXXXXXX

"People will finish updating when Photos is in the background"

I am seeing this message continually. It is persistent since Photos 3.0 on High Sierra for each and every People album that has only manually added faces. Photos seems to be waiting for automatically detected faces for this person, that will never come. For some people I have only one photo, where Photos failed to detect the face. The "finish updating" never goes away for these albums. I ignore them.

I am occasionally sending bug reports using the developer bug reporter, hoping some day the bugs or inconvenient features will be fixed. Detailed and Effective Bug Reporting - Apple Community

With the bug reporter we can explain the problems in more detail than with the feedback form.

There is NO notification or alert as to when names are added, or, as I have discovered, actually CHANGED a correct name to an incorrect name!! Just where and when does this alert appear? I've never seen one!!

Which version of Photos are you using? I am currently running Photos 4.0 on macOS 10.14.3.

I am getting this alert, when I am opening the album of a person and there is a message about additional faces to confirm at the top of the People album, or when I click the command "Confirm additional faces" at the bottom of the album.

When you import new photos, and Photos is scanning the new photos for additional faces, I am routinely clicking the "Confirm additional faces" to check, if Photos mismatched a person. I am doing this before entering name for any one of the new imported photos.

The disaster seems to happen after importing new photos. When Photos is scanning new photos for faces it tries to recognize the detected faces and matches them to the named people. For example, if Photos recognizes the faces in nine photos as Peter, but one of them is actually Paul, and you assign manually Paul to this face, the whole set of eight Peters might get mixed with mixed with Paul, so I immediately go for "confirm additional faces".