Good to see that devs did acknowledge the problem and want to address it.
In a side note I hope they do fix the Indians in AoE2 as well. It is also delhi sultanate, it is only named ambiguously. It is very inaccurate to represent the entire subcontinent as one civ in medieval age.
For AoE2 I believe the most comprehensive civ choices from India will be (even though it can easily use a lot) :
1 North West Hindu (Rajputs or Gurjaras)
1 North West Muslim (Delhi)
1 East Aryans (Bengalis or Oriyas)
1 South Dravidian (Tamils or Kannadigas)
BTW marathas do not fit for medieval age. They came after Mughals who themselves are a modern age faction. Marathas and Sikhs might be good choices for AoE3 if they want to cover them.