> In the south especially, he often struggled just as much as me to communicate with people from his own country, despite being fluent in both Hindi and English.
The languages [1] of the 4 southern states of India are somewhat different from Hindi and other northern, central, western and eastern Indian languages (not too sure about the north-eastern states like Assam, Manipur, Meghalaya, etc., though I guess even they have some Sanskrit influence, e.g. even two of those state names are Sanskrit-based - Manipur means jewel city and Meghalaya means abode of clouds - roughly).
I say "somewhat different" because, some of the the southern languages do have some Sanskrit influence and Sanskrit or Sanskrit-derived words, like the other ones do. I think the others are supposed to have much more Sanskrit influence. For example if you understand Sanskrit you can understand a lot of Hindi, and vice versa. (Studied both in school for some years.)
[1] Tamil in Tamil Nadu, Malayalam in Kerala, Telugu [2] in Andhra Pradesh (and now Telengana, which split off from Andhra some years ago), and Kannada in Karnataka are the 4 main southern languages, although there are dialects of them, and probably some other less well-known languages too (Tulu is one - https://en.wikipedia.org/wiki/Tulu_language ). The amount of variety and diversity on many fronts in India is amazing.
For example, I did not know for a long time that Modi script was an alternative script earlier used to write the Marathi language.
https://en.wikipedia.org/wiki/Modi_script
[2] https://en.wikipedia.org/wiki/Telugu_language - see the part about it being called "the Italian of the East" :) - I used to think that it was because it is lilting or sort of rolls off your tongue, like Italian (guessing), but saw in the article that it is because words end with vowels in both languages.