Move to right place. 
Regarding the suggestion:
Slavery was certainly very much alive in India throughout the era. Sultan Firuz belongs to a dynasty that has already been ousted in 1444 however and ruled over quite a different state than our Delhi sultans do. In 1398 Timur sacked Delhi and most of its empire then broke away to create the situation you see in our start date where former Delhian governors rule as Sultans in their own right in Gujarat, Bengal, Jaunpur and so on
The Sayid dynasty that rule Delhi in our start date are in fact the old governors of Multan, technically left to rule the Sultanate by Timor (though he didn't actually help them achieve that, they conquered what remained of Delhi on their own 20 years after he left).
The above is therefore not quite as current in our start date, not because slavery was dead, it was still very much alive (and was before Firuz as well) but because our Delhi sultanate is something like the Byzantium you see over in Europe, a former Empire with little but its name left to speak for it.
Unlike Byzantium though, Delhi would have a resurgence, the rebels you see at start are lead by Bahlul Lodi who would eventually seize the throne for himself and reconquer large parts of northern India. Even under his time however the sultanate did not come close to mirror the Tuqlaq era and he would not be projecting his power on places like Gujarat or foreign rulers, quite in the same way as the Tuqlaqhs would have.
I probably went on for too long now Anyway I can certainly see a place for general events about slavery in India (we do have some but more related to the Siddis in western India and the Deccan), but the particular policies of Firuz less so
Regarding the suggestion:
Slavery was certainly very much alive in India throughout the era. Sultan Firuz belongs to a dynasty that has already been ousted in 1444 however and ruled over quite a different state than our Delhi sultans do. In 1398 Timur sacked Delhi and most of its empire then broke away to create the situation you see in our start date where former Delhian governors rule as Sultans in their own right in Gujarat, Bengal, Jaunpur and so on
The Sayid dynasty that rule Delhi in our start date are in fact the old governors of Multan, technically left to rule the Sultanate by Timor (though he didn't actually help them achieve that, they conquered what remained of Delhi on their own 20 years after he left).
The above is therefore not quite as current in our start date, not because slavery was dead, it was still very much alive (and was before Firuz as well) but because our Delhi sultanate is something like the Byzantium you see over in Europe, a former Empire with little but its name left to speak for it.
Unlike Byzantium though, Delhi would have a resurgence, the rebels you see at start are lead by Bahlul Lodi who would eventually seize the throne for himself and reconquer large parts of northern India. Even under his time however the sultanate did not come close to mirror the Tuqlaq era and he would not be projecting his power on places like Gujarat or foreign rulers, quite in the same way as the Tuqlaqhs would have.
I probably went on for too long now
Anyway I can certainly see a place for general events about slavery in India (we do have some but more related to the Siddis in western India and the Deccan), but the particular policies of Firuz less so