Presumably almost all competitors from India would be fluent in English (given it is the second most spoken language there)? I guess the same is true of Icelandic though.
The real reason might be that there's an enormous class of self-loathing elites in India who actively despise the possibility of any Indian language being represented in higher education. This obviously stunts the possibility of them being used in international competitions.
Discussions online have a tendency to go off into tangents like this. It's regrettable that this is such a contentious topic.
Your disdain for English-speaking Indian elites (pejoratively referred to as ‘Macaulayites’ by Modi’s supporters) is quite telling. That said, as I mentioned earlier, this kind of discourse doesn’t belong here.