According to many people I have met around the world, having been in about 30 countries, exposed to many other languages, in my 76 years, the English language, either as the original [and for many, their only language], or as a second [or more], is a very difficulty language to learn. The faults, so I've been told, are several, beginning with the fact that English is burdened with more words [well over a million] than almost any other modern or ancient language. Most English speakers have a vocabulary of 20,000 words; a full college education may double that, and daily expected language to be considered literate is 10,000-to-15,000 words. However, daily common use, college or not, is limited to about 4,000 words.
Another problem is grammar; ours is one of the most violated grammars of many, not so much reading, but speaking. We are terrible at slurring words, which makes it difficult for foreigners to learn the language. Further, our grammar rules are legitimately broken even by following such texts as the Chicago Manual of Style, which many professional writers of fiction and non-fiction use as a standard, yet violate it all the time, mostly because even though I feel like my formative education in Los Angeles was a good one, and I was a dedicated student, I never encountered the manual of Style until I was in college. Associated with grammar is spelling [not an issue with speech], which is inconsistent in spite of rules and pronunciation.
My point is that there is a need to cut foreigners some slack while they try to learn English; their knowledge of use of their language probably exceeds our use of ours, and positively our use of theirs. Native Europeans, Slavs, Asians, and Africans have an excellent second language learning of English, much better than our efforts in their language. Our American education seems to have drifted to makes sure we understand how people feel, and not so much on what the know. As long as our students feel good, that's more important than brain training. That's no way to run an education system.