There seems to be a mess now with Issue 7106: Search party also on contact mechanism names - Tryton issue tracker
Contacts are not identifiers.
For example, we have numerous clients and suppliers with an email address ending with
but only one supplier ‘Orange SA’.
But when entering an invoice for Orange it is difficult now to find the supplier 'cause it is not returned in the initial viewable list!
If aliases or abbreviations need to be added, simply creating an anonymous identifier with the value works just fine.