User notes updates with API?

Is this possible update with use of the API a notes field, is visible at user popup

Nope, that’s not supported.

It can be useful, specially i will be able put there nicknames … from the site. Cause now few users can set up same name and email is not visible everywhere! And how to identify user then…

A patron that is subscribed to your campaign cant use two different emails to subscribe to your campaign. So you can identify the patron from there.

Here is a problem of identify at all … i understood that this is not dev question, but … maybe somebody will hear …

No email are visible as ex at messages page.

Still, the same patron cannot subscribe to you with two different emails. So in the api return, if you identified a patron over the email, that is the definitive patron. Your question and problem seem to be related to the site, however, and it cant be answered here - try opening a support ticket at Patreon help desk about that.