Im playing as the arverni but I dont understand the reforms (I destroyed the Aedui btw)

It says:

-Casse, Arverni, and Aedui must build at least 4 (forum)(L3 Market) collectively

Time of Soldiers
Spoiler Alert, click show to read:
-Casse, Arverni, and Aedui must build at least 6 (forum)(L3 Market) collectively
-Casse, Arverni, and Aedui must build at least 4 Large Cities collectively
-Casse, Arverni, and Aedui must build at least 6 Large Temples ('awesome' level)(L3 Temple) collectively


Does that mean if I have 4 cities with L3 markets the reform will happen (what is the name of the L3 market btw?) or does the Casse also need 4 L3 markets?
What will change because of this reform?

And about time of soldiers: Do I need all 3 the things to get a reform and what will this reform do?