OK, finally took out the special fes third from the left. I don't actually know how to take these things without just leaving my idols to it, but it required level 14 (I tried prior image levels as well).
So yeah, since the bottom right fes is unnecessary, I guess this is the hardest one.
Edit: Well, I managed to get all 5 festivals, image level 16, and even took a picture of my results screen... and only half paying attention, accidentally made a new producer over my current save. I think I'm done with this game.