I'm definitely not trying to be snarky or mean here--just offering my take on this after reading the article. English is obviously the author's second language, and I would offer that practicing English and learning better fluency/grammar/spelling would help an order of magnitude more than practicing computer science quizzes and coding challenges. Many of the candidates and developers I encounter may or may not be good software engineers--I don't know because their language skills are lacking, and they are unable to convey it through spoken or written word.

I'm learning a second language myself and I feel your pain. I would never want to interview in a second language. However, in the US workforce, English proficiency is critical and such soft skills can often mean promotion into management, increased responsibility, and technical leadership positions.