Vanilla Reform

[Raygereio]

Well, it needs to be a huge city (24.000 pop) and owned by the Romani faction.
If the AI Romani isn't doing to well, then they might simply not be queing up buidlings as the AI probably reasons that he needs the money to produce units.

If you find it impossible to get the March of Time event with the add_population and process_cq cheats, then get the force diplomacy mod and simple buy a city in the Italian peninsula, upgrade it to huge level and then sell it back to the Romani.
I never tried that, but I've heard it works.

Also, as the only upgrade for Pontus and Saka from the MoT event is their bodyguard, you could also just jump in the EDU and change the pre-MoT bodyguard (general_unit) to the post-MoT bodyguard (general_unit_upgrade).