My question is for a friend of mine who is saying that we can’t be sure to curse in qunoot, I have seen the Hadith of Imam Jafar Al Sadiq (as) doing so but he said that we can’t just follow what the Imams (as) did so is it allowed to curse in qunoot?

Cursing the enemies of God is a dua. It is asking Allah to remove His mercy from the evil Individuals. If this is done with the intention of a dua then it is allowed.