I dont think getting back 250coups per 1k ingots spent is fair at all. The only reason why players spent so much more money on this event than they usually do on others, is because they got back a fair amount of coups along with other rewards for those 1k ingots (atm am talking about the 1st two days while it was actually working).
I'll just give you my example, with each 1k i spent i got back at least around 1,5k.
So going from a reward of approx +500 to a "refund" of -750 isnt fair at all. You should give the rates a better thought.