I like the idea of the long feeding duration, and the additional currency, and if the static goods were worth it, I might place the building for that (and the aesthetics). The additional currency would get you one or two (depending on continued increase in costs and decrease in rewarded currency) additional chests (and the rewards in the chests are not always superb). I also like that Elvenar always rounds up (even where the standard rules of math dictate to round down), which actually makes it work out to a little more than the 1-2%, but not by much. If we could teleport this out, it might be worth it.Yes, every event, if you feed it during each event. And the amount starts at 1% and increases to 2%. So in an event like this one, that 2% bonus means about 110-120 total extra event currency, if you complete all 75 quests.
I just don't think the static goods, culture and pop are worth the 4x4 footprint. It is 65% of the mana and T3 goods that the owl provides for the same footprint. It has comparable population, but way less culture than the golem, witch hut or owl. It isn't enough T3 goods to replace a manu, or enough mana to forego another mana-producing building. It is pretty, though. Even the blue egg for stage one is such a great colour.