Hinglish mixes Hindi and English, often a Hindi sentence frame with English nouns, and it is written in Roman letters, in Devanagari, or in both. A typical office sentence is “Kal ki meeting mein budget approve ho gaya, Rohan next week tak PO bhej dega.” A transcript of it can come out in Roman letters, as कल की मीटिंग में बजट approve हो गया with English words kept in Latin, or as a pure Hindi sentence with the English words translated. Each is a different result for the person who reads the minutes, so decide which one you want before you test.
The Census does not count Hinglish speakers. The 2011 Census recorded each person’s mother tongue as the language their mother spoke to them in childhood and sorted the replies into 121 languages; Hinglish is not among them, and it is not one of the 22 languages in the Eighth Schedule.
Script also changes cost. The RomanSetu paper found that romanised text cut token counts by 2x to 4x compared with native-script text, and that, after extra training on romanised data, a Llama 2-based model matched or beat native script on several tasks. An off-the-shelf model may not behave the same way, which is why the tests below use your own text.