Assyria too.

I think considering Nepal and Bulgaria were in the same data leak I think that those civs are guaranteed and will be in Right to Rule. At least I think it's more reliable than the apparent cut content one involving Iceland and the Pirate Republic.
We actually don't know if the content was cut, so much as some of its prep code was pre-released. This does happen in many games where current patches accidentally reveal some surreptitious features of patches planned in the immediate future. This can happen for many reasons, whether content was developed at the same time and then meted out, or was initially planned as a larger package, or simply released in a different order than anticipated. We really can't know why, and we definitely can't presume all five civs and all three leaders
weren't cut, but for now I think it is safe to suggest that the "general idea" of a "naval expansion" is probably planned at some point between now and the first major "expac-like" content release. If we don't see it within a couple years I think it will be safe to suggest it was cut/retooled.
The "Exploration Age" is European in name only. Cultures worldwide experienced similar challenges, changes, and conquests. Look at the massive conquests the Ming pulled off in the 14th century. Islamic expeditions for spices. Morocco's invasion of the Songhai. A quest for resources, land, and autonomy from a larger state were absolutely not a singularly European phenomenon.
Also MONGOLIA exists. I am generally okay with exploration era being depicted as treasure-fleety since we did see that in Northern Africa, the Middle East, India, Macronesia, Polynesia as well. It's a very one-dimensional portrayal of the era, but as I have already stated, I think the eras are
deliberately oversimplified and will only be given more facets/nuance through specific civs, leaders, and wonders, rather than universally chock-full of analysis paralysis. We already see suggestions of this in Mongolia and the Bulgarian wonder.
While I am not defending the choice of the stepwell for the Mughals, because I 100% agree it is wholly improper for that civ, I am taking that design choice, as well as Nepal's overall mishmash, to mean that a lot of "edge case" civs actually stand a decent chance of being fudged into the roster. I am not sure where the line will end up being drawn for me at historical inaccuracy ruining the game, but so far the Mughals and Nepal are not it.