Yeah, yeah, of course. I am not saying they weren’t. But there are two goals: (1) Not oversaturate the number of civilisations in the game (2) Choose the civilisations that are most appropriate for the timeframe selected. As I said, we could have 15 different civilisations in the game from Bahamani to Sultanates to Guptas to what not, but we need to make sure they are all unique and differently playable. In my opinion, “Bahamani” as a civ doesn’t necessarily represent the medieval deccan as much as the Kannadigas. However making them a gunpowder civilisation certainly shifts the timeline to include the cannon-armed battled between the different Hindu, Persian, and Turkic kingdoms in the southern deccan. so that is indeed a good compromise (while also giving the cavalry and infantry of the earlier centuries a strong representation). Anyway the locals in the Bahamani Sultanate were the same Kannadigas who lived under the previous empires too.
As far as the northern Sultans go, they might have been of Turkic origin, but they certainly used Persian in their daily life and in courts going all the way back to the Ghurids. Every single one of them: Ghurid, Khilji, Lodi, Mamluk, Tughlaq, and Sayyid. Of course the Mughals till Shah Jahan also had exclusively Persian, and Persian was scrapped as an official language in Delhi only in 1857.