Now for the sake of argument, let's give you the benefit of doubt and assume that only 5% of the rapes in India are reported and 95% cases go unreported. Also assume that 100% of rapes in USA are reported. By that logic, the real rape rate in India will be 0.4 x 20 = 8. Now let us go further and double that too, we get 8 x 2 = 16, which is still way less than 27.3 (the rape rate in USA).

The guy who made the long post accounted for that - he's effectively saying 97.5% of rapes go unreported. My family's from India - I hate seeing it on the news all the time for this shit, but I know it has a deep problem with gender equality even when it doesn't manifest as a crime, never mind something as bad as rape.

That said, I'm also interested in stats, and especially how to figure out accuracy when the sources are limited and unreliable. It's very easy to get horrific stories in a country with 1.3 Billion people. But it doesn't mean you can outright dismiss the reported stats. A 40x multiplier from the OP is quite massive.