I think the general consensus is that you need to be more generous with the rewards. As I'm sure many people have pointed out in previous comments, acquaintances are not a very good reward. You're asking people to exchange 10,000 gold to merely get the opportunity to try and get their prize.
Perhaps it would be a good idea for tiered events to have an approval instead of an acquaintance for the final tier? or if you're going to host acquaintance events, at least beef up the amount of pearls, agates etc... that you get for completing all the tiers.
As it stands, you would get a total of 230 points from this event, however Freya has a 0/4000 friendship rating. I've heard you don't play the game, but if you do not get the approval of "x" hero within the time limit, they leave, along with all the pearls etc you have used on them.
This means it's highly likely that exchanging 10k gold for this event will leave you with only spirit stones and water vials...
Another thing you could do is place the major pearl chest in with the rewards for the final tier, and have an epic hero approval as the raffle prize.