Although English is the official language of Cambodia, actually not many people can speak English well. If you communicate with people in Cambodia in English, the junior high school level will be fine, and the other party can understand each other together. The English spoken by ordinary Cambodians is definitely very different from the English pronunciation in American TV series. Celebrities, national leaders and stars in movies and TV series are another matter.
Cambodian English is no match for Indian English. India was ruled by Britain for a century or two, and English was their second language. I have been exposed to English since I was a child, so many Indians are fluent in English. It's just a local flavor, and its grammar is sometimes different from the English grammar we usually use (this rarely appears).