I personally think that all Indians problems have originated from a big fundamental design flaw (not meaning any offense to who design the civ, but it does have some problems from the beginning…).
The Indians completely lack a unit line, which is the knight. Now there are other civs that completely lack unit lines before the Indians, and those are the meso civ, so let’s look at how the resolved this.
The meso civ completely lack any cav unit, to complement that, they gave them similar unit that can fill the cav spot, but that also change the gameplay enough to feel the difference. This was made either in the form of a regional unit (like the eagles that substitute melee cav) or in the for of an UU (like the plumes that substitute the lack of CA).
Now this was relatively easy to do, because this new unit won’t break the balance of other standard units, but it would just fill a vacant spot, and without being tied to the old unit, there was the possibility to really build them from zero, and balance it as it would better fit the civ.
Now what was instead done with the Indians? The Indians lack only the knight, still this was a big problem since it’s one of the 2 most commonly seen units.
So instead of giving them a units that fill that spot, they buffed a standard unit that already filled another spot, and this without removing what make them good on that job (its anti Cav properties).
So they gave to the camel some of the knight properties, like more PA, more HP and atk (from the IC upgrade) and a better atk vs buildings. But all of that without adjusting its anti cav bonus.
This had the consequence of giving birth to an hybrid unit with a degree of resistance to range attacks and and further strengthen anti cav role, given by the knight-originated buff (more HP and atk help in every direction).
So an OP unit too versitile and further strong at what already excel at, but that at the same time doesn’t really substitute the knight (otherwise it would be a paladin with an anti cav atk).
You see how a simply flaw design originated 3 different problems. On top of that their UU is useless, but not useless for its stats and cost (well, that too, but it’s another problem) but useless because it does nothing to supplement into this void that Indians have. The cherry on the top is that Indians also lack the arbs, the last upgrade to the other most used unit line, meaning that they can’t go for knights and neither for fully xbows into arbs.
So, to conclude, I think that there isn’t any simple solution to the Indians problems, if not through an deep re-design of the civ in general.
Instead of buffing so much their camels, they could have given them just a small buff (like for example +1PA alone without the IC, or nerfing the IC itself) and they could have given them a cavalry castle UU that can actually fill the void of the knight line, or given them a different regional unit, like meso civs have the eagles.
Either way, This would require a lot of other complementary changes to their bonuses and tech tree that would basically redesign the civ from the scratch.
