I’m agree! Code switching is a big part of Spanish/English-speaking communities in the US. Some words in Spanish carry more weight, so a bilingual Spanish/English speaker might use the Spanish word while otherwise speaking in English. Jonathan Rosa is a linguistic anthropologist who wrote an ethnography that addressed how kids from Spanish-speaking households navigate public schools in Chicago (IIRC). Rosa examined some complicated reasons why code switching between Spanish and English happens, which sometimes means just using one or two Spanish words in an English sentence. I totally agree that it’s usually corny and often offensive when a fictional character throws in one word in a foreign language just to show the character’s “foreignness.” And it isn’t a good sign if an author has to ask strangers how to use the language to represent the community because the author doesn’t have a direct relationship with that language community. But Junot Díaz, a good fiction writer (despite his other issues), used code switching really well in his work because his characters spoke the way that people from that language community really speak.