Actually this is a bug. I can not search for people because Teams can not find people based on fractions of their names, ex:
"Rodrigez Yazvedo, Juan Maria" can not be found by typing "Juan Yazvedo" nor "Juan Rodrigez".

Teams is unable to find a person, unless I know the person's made-up Teams name (family name comma first name), and start typing a string that is contained as an exact sub-string within the made-up name.