Given that you only have, usually, one Era in which to found cities using that list, it's a safe bet. On the other hand, they've said that you can choose to keep the same Faction in the next Era (and all the way to the End of Game? I don't think they've specified that yet) so there will have to be some kind of 'overflow' list enough for, say, Assyrian Cities in 3 - 4 Eras.
The big problem, which has been gnawing away in my mind ever since they first announced Factions like the Harappans and Olmecs, is how they are going to generate any legitimate City List at all for either of those.
They can tease out some Harappan city names from 'back-dating' later cities in the region, many of which coincided with Harappan sites earlier, but it's tricky: so far the consensus is that the Harappans spoke a language pre-Indo-European, so largely unrelated to the later languages in the area.
But Olmecs - we got nothing. There are paleo-linguistic studies that have put together tentative vocabularies of a few Olmec words or phrases (actually 'Epi-Olmec') but absolutely nothing even resembling a place name or city name. I looked into this a couple of years ago because there was a really good Olmec Civ modded for Civ V, but with the modern Spanish archeological site names, which drove me crazy.
Unfortunately, couldn't find anything more useful than to name cities with the Epi-Olmec words for 'Turtle',' Jaguar', 'Serpent', 'Eagle', etc. Still complete fantasy, but at least they looked better than some completely foreign word imposed from Europe.