Playing on the west’s ignorance was the joke, and him convincingly reeling people in for interviews was the comedy. Not the character itself, the reaction to the character.
Your points are voided, in any cases.
They were a vehicle to poke fun at ignorant westeners.
How could one tell?
- Kazakh people (mostly) look nothing like Borat
- It was clearly (to me, a European) set in eastern Europe
- Cohen played on our ignorance to make us believe Rumania is Kazakhstan
- Everybody he encounters thereafter is American
- Cohen uses Borat to mock stereotypical American[0] behaviour
- I am aware just how much juvenile humour there was too
[0] applies to most places, but the film is set in America
Jewish people portrayed as greedy is an existing stereotype with a sad history. There is no such existing stereotype for the people of Kazakhstan in the target audience of the movie.
Also, say what you mean. Raise eyebrows? So what. The last Star Wars movie raised some eyebrows. This thread already has enough people righteously missing points, so just say what you mean.