I'm wondering if there's a way to play scenario maps like "Age of discovery" with random AI civs, appearing in random locations.
It's certainly possible to play on any Scenario's base-map as a new mod, either using the Scenario's tribes, or the epic-game Civs.
And for the Scenarios like Mespotamia and Sengoku, where you build your entire Civ up from nothing, the base-maps should be relatively easy to mod to replace the starting units with 'generic' spawn-points, so that the tribes (again, either the Scenario-tribes, or any/all of the epic-game Civs) could start anywhere.
But for all the other Scenarios — RoR, FoR, Middle Ages, Mesoamerica, AoD, Napoleonic, WWII Pacific — which all start with preplaced cities (all assigned to a specific Civ) containing multiple buildings, Wonders and units, I don't
think the (Firaxis) Editor allows any way to (re)assign a preplaced
city to "Civ=Random", i.e. you wouldn't be able to play as e.g. 'Aztecs, but starting in Madrid + Toledo, with all the Spanish Wonders/buildings/units'