That is really too bad, especially if you are in a position where you are too distant to talk to these people in person.

It seems really odd that he wouldn't have been diagnosed already, but that scenario seems more likely given what you've said (as opposed to him being diagnosed and not informed). I'm not an expert, but I don't think you can get that kind of diagnosis without the memory or cognitive tests. It doesn't sound like he would hide this from you, given how up front he is about his health, so it really is a difficult situation.

I can see it happening that no one has really noticed enough to get a diagnosis - or that they are scared of one.

What do you think about contacting the doctor? Does his family refuse to speak with you or just not welcome it? Does he mind if you talk to his family?