I'm not sure how it complies with your idea to have Indian Presidencies gaining parlementarian vote : by the end of XVIIIth centuries, these were arguablr rather limited territorialy and roughly homogenous ethnically, except in Circars.Interesting points. I wonder if there's an opportunity for a place like India where no one ethnic group has a majority, unlike Algeria? The British did expand the vote (albeit with limited powers) to the assemblies in our timeline.
When British India becomes larger (and the ethnicisation of the territory becomes a thing trough colonisation, at least partially) you'd have more diverse territories but less chances to make it turn early to partial access to British institutions.
I could see, however, an equivalent to the old communes of Senegal (the english article is somehow incomplete : if you can, go for the french version for the late XVIIIth), complete with pitfalls and obstacles, within the frame of British India.