I have bumped into some language forms that seem to defy machine translation so far.

A friend of mine is from Vanuatu, and usually posts to social media in his native written Bislama. It's quite beyond my ability to understand. Maybe if I were to live there for a while I would pick up some of it.

https://en.m.wikipedia.org/wiki/Bislama

It's led me to wonder about other languages which may be the result of mixing languages encountered by populations that experience lots of migration. "Creole"?

This phenomenon has often been discussed in the context of colonialism, one culture wishing to dominate another, but I'm pretty sure its more general than that.

I recall a friend of my roommate in college, who worked on a fishing vessel for a summer and came back with a pastiche of Japanese and Portuguese, enough to participate in the most important activity on the boat: placing bets on Japanese high school baseball matches.