I think some people are beyond help, but do you guys have any success stories?
Nope. Islamic intellectual dishonesty is impenetrable.
Still, it's always worth doing some refutations of the b.s. miracle claims that Muslims toss around these days. I was actually thinking of starting my own YT for this purpose, as well as for addressing other theistic arguments.
I'm presently in an exchange with a Muslim who's a hafiz and is fluent in Arabic so he can't exactly be ignorant of Islam's teachings. It doesn't matter how many things I point out in the Qur'an that are simply nonsensical, he simply doesn't seem to consider that maybe the Qur'an isn't the infallible word of God that he thinks it is.
As an example, I mentioned verses 6-7 of surah at-tariq (you know, the ones that say that the male and female gametes come from the backbone/ loins and the ribs, respectively) and he just said, 'Yeah, so? That's true isn't it?'
I think that people have to start questioning it for themselves. If you can get them away from the presupposition that it's the word of God then their own common sense will do the rest. But therein lies the difficulty.