2) Most people don't "consume" literature or poetry, and it's unclear to me that non-performance art requires language. (I appreciate Rennaissance painting, but apart from the occasional Latin writing I don't need language to understand it.)
Disclaimer: Besides English, I'm reasonably fluent in Spanish (more so 35 years ago when I last lived in a Spanish speaking country), and used to be reasonably fluent in German, French, Tzeltal and Shuar (and a bit of Italian and written classical Greek). So I have every reason to hope this study is correct. But I have my doubts.
In Latin America, most countries speak Spanish (with the obvious exception of Brazil and smaller colonies from the other European countries), so the every day pressure to learn another language isn't there and English becomes the "obvious" choice. I don't quite get why you seem to discount English entirely.
There's always been a Lingua Franca. It hasn't always been the same one. There will likely always be one.
Where they do, there needs to be a coincidence where words with multiple definitions happen to have the same meanings in both languages, or there happens to be a similar saying in the target language. Often this is not the case. Translators often just make up entirely new material to substitute in for that.
It will help you communicate, but not partake.
AI won't be able to succinctly translate that joke and have it hit the same way. As an experiment I just fed that into ChatGPT, and it did explain the pun in 6 paragraphs with quotations and a bulleted list, but that kills the simplicity of the humor.
If I changed the meaning of the sentence, I could say, "can I study civil rights if I'm a lefty?"
If it were text, I might give you the translation I already gave yesterday and add a footnote explaining the pun.
Neither of these are ideal. One changes the meaning, the other is hard to understand.
What's the problem with an LLM-translatoin bot doing it? It would just do that, give a possible translation, and explain the issue.
That said, there are plenty of jokes in English. Stop me if you've heard this one...