That distinction matters for the hundreds of millions of people who write Hinglish every day. They do not need their words translated — they wrote them already. They need those words in the script they belong to, for a greeting, a formal message, or simply because Devanagari looks right.

Under the hood, a transliteration engine is mostly a mapping problem with judgement calls. Roman letters are ambiguous: "a" can map to more than one Devanagari vowel depending on position, and combinations like "kh", "chh" and "aa" have to be read as units, not single letters. A good engine processes text greedily, longest-match first, and keeps the rules predictable so users can guess how a word will come out before they type it.

The practical test is speed of thought. If a user has to stop and think about how to spell something for the machine, the tool has failed. The best compliment a transliteration tool can get is that people forget it is there.

If you want to see the idea working, the live tool behind this post converts Hinglish to Devanagari as you type, free in the browser. Type the way you chat; read it the way it was meant to be written.