I changed my opinion.
The card absolutely needs a rewording, because with the current wording, it doesn't actually do anything. It triggers when you buy something, but at that point, no curse is being gained so there's nothing the ability can replace, and that means your opponents aren't getting cursed either (for the same reason that revealing 40 Traders or the same Trader 40 times only gives you one Silver - in order for the ability to work, there has to be something it actually replaces).
It should be something like "When you buy a curse, the next time you would gain a curse this turn, etc" and in that case you could choose the order of the effects, but only the first one of them would work.