I have been playing Pahlava for some time and I managed to reach that building queue above to get Reformed Government. It is impossible to build Reformed Government in some homeland provinces like Nisa, Khiva and Alexander, Asaak, Antiocheia-Margiane, Alexanderia-Ariana (Nisa and Khiva is about Nomadism I guess). In most of my cities I am not able to build law or culture buildings necessary to support public order.
Also, I managed to build Reformed Government in Charax which is a subjugation land. However, I cannot build Reformed Gov't in other Hellen-influenced subjugation lands. I'm really confused..
After I had conquered Babylonia and Seleukeia, I was able to build all building available to Reformed Gov't. Since I destroyed Seleucids' goverments, I installed type 4 governments and now it is not possible to build anything two or three culture buildings and regional MICs.
And why is not any type 2 or 3 gov't for Pahlava? If Reformed Gov't cannot be built, there isn't any factional military or law buildings. So, I've got lots of cash and nowhere to spend it.