Sueña and suena are two different words- no relation, although they look alike to non-Spanish speakers.

Suena, sueno, suene- from verb sonar, to sound, play, strike, etc. Also takes the place of our "sounds like," or "reminds of." A number of idioms with it.

Sueña, sueño, sueñe from irreg. verb soñar, to dream, to daydream. soñario, in dreams.

In Spain, gringo is an 18th-early 20th c. word for a foreigner, usually English or American. Now largely replaced by extranjero.
Gringo in Spain lacks much of the emotional baggage it carries in North America.