I think the intention of the thread is in the right place. A lot of people do play bilingualism wrong, and sometimes even downright offensive, the ones who use "dumb-speak" by just randomly removing words to sound "foreign", not understanding that this comes from a misreading of grammar, like how a Swedish person tends to mostly get plurals and singulars wrong, but is overwise pretty accurate.

I think the theory this thread proposes is inaccurate, from a personal experience as a polyglot living in a different country and someone who speaks with people who code-switch. As a person with a strong interest in linguistics, let me first address some referential mistakes you're making:

• Hindi is a very bad example for code-switching, because it much like other ex-Anglo colonial nations, "suffers" (debatable) from severe linguistic barbarisms. for those reading who don't know what this means, barbarism is when a word is wholesale adopted from a different language, and made part of the native language. A good example is the word "Cuisine" in English. This is a French word and it was adopted 1:1 (even if this is technically a bad example since that word was adopted as a consequence of the Norman invasion of England, and so technically not a barbarism because the upper class spoke French). Anyway, Hindi is a bad example because this does not feature code-switching, many cosmopolitan Hindi speakers are bilingual with English, and the Hindi language itself features many barbarisms or idioms that fulfill linguistic gaps within the native Hindi language at the time of Colonialism. A good example is "C'est la vie" which is a French idiom, but one often used in Dutch and Uk English, because this idiom does not have a good equivalent in these languages, and it is used by people who do not natively speak French. This does not mean they are code-switching, but just using an adopted expression.
• Secondly, people who in fact say "How are you, Amigo". This goes a bit into cultural isolationism and cultural segregation in America and I won't touch upon that subject, but it's a common form of street language retention. A good equivalent for myself is ex-colonial immigrants who speak a Creole version of Dutch, and then shift language to what we call "ABN" Dutch. They however still retain some words as a means of expressing their culture (and some of those expressions even in the Dutch language in itself as they contribute to the development of the language). Similarly, "Amigo" is used as a derogatory reference in American English by people who do not even speak Spanish, in the same way, that "Sweetie" is used in the South to be endearing or demeaning in variance.

So, the example I would have used would actually be a French one:

• "Oui, I would like to have a sandwich, sil-vous-plaît." - This statement makes the assumption that a French person doesn't know the word "Yes" and "Please", even though they are some of the earliest learned words, or so much choose to replace them for whatever reason. This is often bad expression of bilingualism or expressing the foreignness of a speaker in media that does not carry over to the real world. People do not replace simple words, they replace complex words. Because here is the crux:

English is a dumb language. I think any non-English speaker can agree, it has no gender conjugation, no formal case, the grammar is all wrong (in comparison to continental languages), and it generally is very easy to learn. This means it's great for a "world" language that everyone speaks (it's even implied that the internet is operatively English, this is in no way an expression of lack of intellect for people who only speak English), but it means that during fluid conversation you have to code switch to fill the gaps that English cannot express due to its limitations. You have this explanation the wrong way around, non-English speakers do not randomly break out into English (or Common) to express jokes, or words or sentences, people code-switch when they do not know the right word to use, specifically because English as a language on average lacks about 40,000 words when compared to other languages, in particular in the field of compound words. Here are some examples of me code switching:

• I code-switch to people who speak Dutch like Waterdruppel when I want to talk to her in private while in a large group of people and I don't want to have them understand who we are talking about.
• I code-switch to people who speak Dutch like Waterdruppel, when I am looking for an English word that I have forgotten, or it flat-out does not exist. For example the word "somber" (the feeling of looking at someone and grasping a flash of their life, and understanding the sentiment that this person has feelings, dreams, ambitions, and a history of their own, but you will never experience that flash or meet this person ever again). I just spent two sentences explaining a single word, and while this is an exaggerated example,  our languages are full of these.
• I code-switch to make a joke to someone in a language we both speak but nobody else is fluent in. Case and example, me, Carl, and Jall speak English to each other. Carl does not speak French, but Jall and I do. I will sometimes make a joke to Jall in French, which Carl will not understand, but Jall will reply in English because he is mindful of Carl and does not want to exclude him.

So in short: Code-switching occurs when we: Want to talk shit, Want to use a word (or idiom) that doesn't exist in the language we are speaking, or want to make a joke in our native language.

This gets a bit more complicated when you consider internal monologue, but I won't get into that because internal monologues aren't consistent across all humans, I think something like half of all Humans has no internal self-examining thought, and while that number is probably proportionally higher on Massive, nobody benefits from an explanation on how to code switch in your internal monologue because you can't roleplay this.

I think this summarizes it. I wanted to correct the incorrect example of the Suvial and the incorrect example of Hindi because they replace one bad form of code-switching with an arguably even worse one.