Building off of my suggestion earlier in this thread, I propose adding a new wonder... The Great Bath of Mohenjo-Daro (this wonder was also represented in Civ 6). This wonder would take the effect currently held by the Aqua Appia (+2 in all cities), and would help inspire either a Great Engineer or Great Prophet. I see this move as having two benefits: First, it would give the Harappans a wonder to build, as I think they are the only early civilization without a wonder that represents their culture. Second, it would mesh really nicely with the Harappan unique ability (positive contributes to city growth in the ancient era), and help inspire a play style that doesn't require spamming out city builders to meet their 30 population requirement.