My suggestion is to upgrade a bit this event to do it more appealing to players.
Well, in the first hour of this event, tanakas should drop the same amount of yang as when this event is combined with gold fever (I think is x3). This way it would be worth to go and kill like crazy these things and that way maybe the next day one doesnt need to see a desert full of tanakas because no one participated.
If x3 yang is too much, x2. But I dont think it's unbalanced. I once participated in a tanaka hunt + gold fever with my 92 and I did around 110kk in 1 hour (it was only 1 hour that combination). With vein spawn one do much more yang with soul crystals and like tanaka hunt is each 2 weeks. With metin spawn event I always do 150kk+ with red changers and with boss spawn one can do 100kk too.
Another thing I'd like to suggest (it's not really important, but well) is the possibility to pick up the yang from tanakas with third hand. But NOT the last batch of it, only the ones that gives you 80, 90, 100 yang.