It would be great to group an unnamed person that is found and displayed in many separate sesection and that you do not know his/her and name. This will improve Lightroom CC to also recognize the same unnamed person and therefore limiting fragmentation of the same unnamed person.
Basically, I proposed allowing people whose names are not be known to be flagged as "Unknown Person" so that they can be removed from the "Unnamed People" bucket, without deleting the Face Region (e.g., in case their name becomes known or relevant later on).
This would go nicely with the ability to group unnamed people.
It's also worth noting that Lightroom CC is a bit better at this than Lightroom Classic. E.g., If you click on a group of photos of a person, it might ask, "Is this the same person?" That allows unnamed people to be grouped together—and, as you note, this gives the machine learning more input on who that person is (and, perhaps equally important, who that person is not) by confirming their identity.
That said, to my knowledge, Lightroom CC doesn't allow you to explicitly group people; this only works if the machine learning suspects a duplicate.
(I acknowledge that Lightroom CC uses an entirely independent facial recognition system—and also that it is much better at grouping similar faces regardless of whether or not they're named.)