Most medieval fairs, or at least the better ones, featured I fabulously showy and fantastic religious event.
And when I say showy and fantastic, I mean showy and fantastic. By the time you got a fair out of these events the priests were just around for the sacraments and the whole thing was being run by various economic interest trying desperately to outdo each other.
We have scripts from some of these spectacles an they put Shakespeare and Greek Theatrical festivals to shame for length and insane theatrics.
In FR the spectacle would be INSANE, not only would you have to include every religious group in town, no doubt resulting in a myth of such a complicated variety that it took a mage versed in arcano-calculus to storyboard it, but at least one of your economic interests would be the red wizards and then every other economic interest would have to hire their own illusionists, adventurers, and summoners just to compete.
With the spectacle up the numbers of onlookers would go up as well. I mean the point of medieval spectacle was too draw a crowd not only with a spectacle but with a multi-functional spectacle that also sold you things, stole from you, gave lesser spectacles like knife throwers, gave you your military training, legal recourse, and saved your soul. It was the original full service stop.
In FR with so many more services....
...you are talking real fantasy with everything much huger, stranger, more wonderful, risky, and exciting than even the things we get in real life now.
Picture disneyland crossed with Bangkok, the Vatican, and Loviator mistress of pain.
Shaved gorillas are just the appetizers, and pick pockets who go for money the lowest risk....