These sentences are full of American-English idioms. They are all correct, but they don't sound like the work of non-native speakers who are learning the language.
Plateu is not redundant.
fluff-free means without any unnecessary embellishments
Iowa is a state in the US that is in the middle of farm country. It is considered to be the epitome of middle-class average America. Un-Iowan means entirely different than what you would expect to find in America.
The other phrases all use correct usage, but they sound like the kind of writing that I usually get from native-English speaking college students, not EFL or ESL students.
- For Teachers