Impossible to verify any of this stuff. Why? It's how they work the numbers. eg. If a person was "born into" a religion, but then becomes an adherent to another, some religions chalk that up as a "convert". eg. Protestant Churches are filled with "ex-Catholics", many of whom were never adherents to Catholicism and wouldn't know dulia from latria, but merely found Christ in a Protestant context so identify as Protestants. Vice-versa as well.
YTube and other atrocious websites are full of videos of people that converted to Islam from "Christianity". Of course, quite often they were never actually Christians, just came from a family that was nominally Christian perhaps decades ago.
I'm sure the same can be said of people converting to any religion.
What's more, religious "growth" figures often work the same. You've heard ad nauseam about such-and-such a religion being the "fastest growing" in the world. Often that just means that they're busy making babies, putting those children through the prescribed initiation rituals and notching that up as religious growth.
You just can't trust the spin doctors.