What if someone did an action expecting to bring harm but ended up bringing only happiness?
Well then, I guess they saved themselves and others from a host of suffering then! But realistically this merely shows that they had ignorance of the consequences of the action. It could also be that the victim did not have the requisite karma to experience suffering from the action OR that the victim has developed their mind to a point where it is not swayed by the eight worldly dharmas. But really, only a Buddha can know the exact consequences of a particular action. This is why, before one has developed a degree of wisdom, it is smart to engage only in actions that are considered wholesome by the Buddha and avoid actions that are considered unwholesome.
That perspective would be dissatisfied but the sentient being causing the action would lose attachment to the dissatisfied perspective as he would be only bringing happiness therefore avoiding attachment to dissatisfaction.
Want to rephrase this? It doesn't really make sense.
I guess one would need to have complete control over ignorance in order to want suffering yet bring only happiness...
Refer to the first answer.
Well then maybe it actually isn't the desire of suffering then as it brings only happiness. I guess the complete desire to bring happiness is just as good the complete unsuccessful desire to bring suffering.
Ummmm... no. You see if your intention is to cause harm and you mistakenly cause happiness YOUR mindstream will still be effected by your intention. It is more than possible that you will feel ever more anger, hatred and aversion due to the victim experiencing happiness and thus cause even more suffering for yourself.