my feedback of this event while it about to end:
I really liked this event. I found quests very good, very doable for both small and big players.
prizes were a bit less to my taste, but tastes differ (i know some people adore seed and mana buildings but i just dont like them), i personally like building that give you population.
setprizes had more then one chance to be obtained which is good, im not sure it was a good idea to put one of the setprizes as 3rd main prize tho. having it as first and second seems like a better idea. 3rd puts many people at risk of not getting it while they were going for full set. I acknowledge thats probably because you hope those players would spend diamonds on it, but personally i dont think its a good idea to force/trick players to spend diamonds, just give them the feeling they want to spend them. (forcing them turns into resent and no longer willing to go for set in next event)
Whishing well, well good idea to be able to get diamonds, 100 days till expiration is maybe also a good idea compared to FoE with permanent wells which result in diamond farming citys. However, i do not think the prizes you get out of the well are well balanced, the amounts you get out of it for the last chapter are demoralising compared the the size it takes in your city. (compare it to benefit of a max level house, or workshop, or manufactory in same ratio)
The diamond amount i think is fine (tho of course who wouldnt want more), im sure you caculated to find the exact sweet spot between not too much and not too few.