There is such a thing as Indian English, maybe not officially but it certainly exists and it does differ from British and American English.
As a matter of fact, if you look up prepone in Wiktionary "prepone" is mentioned as being used in India, so it's not that weird that the teacher in the article used it.
As a matter of fact, if you look up prepone in Wiktionary "prepone" is mentioned as being used in India, so it's not that weird that the teacher in the article used it.
https://en.wiktionary.org/wiki/prepone