In the game, the festival building is described as follows:
Festival
Costs:
-20 influence
Provides:
+2 growth when city is idle
Which makes the building practically useless. But, actually, the festival provides +3 growth in idle cities, and +1 growth otherwise, which makes it a rather useful addition to any city.
I believe the description should be:
Festival
Costs:
-20 influence
Provides:
+1 growth
+2 additional growth when city is idle
