The writing system that developed with Sanskrit and that's still used for both Sanskrit and several modern languages of India is called Devanagari.
They could also, for example, have support for Nepali, which is also normally written in the same alphabet but is definitely a different language from Hindi. In that case the language support would be different at a software level, like the vocabulary and/or grammatical patterns that the speech-to-text system is trying to recognize.
The problem (whether for a computer or a human being!) of figuring out what language something is actually written in can be tricky when many languages use identical or related scripts:
https://en.wikipedia.org/wiki/Wikipedia:Language_recognition...