So, I’ve spent years learning Hindi and Urdu, and as part of that due to long conversations with friends and colleagues in India; I’ve also needed to learn the Hinglish dialect. UK and American English speakers often see these differences as "wrong," but Hinglish is a fully coherent and functional variety of English. In fact, as I'm sure you probably know, there’s no single correct version of English. Hinglish might even be the most widely spoken variety of English in the world.

With the word gravy here, you've identified a dialectal difference between Hinglish and American/UK English. They don't use the word curry unless referring to the leaves it is always called gravy. Besides this there are many words like this that have shifted between dialects. For instance, gram in India refers to what I would call a pulse, ladyfinger means okra (while in American English, it’s a type of cookie), and brinjal is used for eggplant in Hinglish. Interestingly, brinjal isn’t a native Hindi word but a Portuguese loanword—it’s only used in Hinglish. When speaking Hindi or Urdu, I would say बैंगन (baingan).