I considered that as well, but then instead of gathering the materials we could find their stash already completed that they use to do so. Also possible that the powder needs purification technique to use, not their corrupted bullshit magic. They might have their own way of communicating, as well as basically what I suggested for the demi humans above, they get like otherwordly suggestions and ideas forced into their brain but non of them can have a proper conversation with the Father. which is why there is so much miscommunication in their ranks.
Also, the game says multiple times I think but the Father is not even it's name, it's just some bullshit the cultists came up with. So definitely they can't exchange words, not enough for a proper introduction even.
If I may draw even more parallels to Bloodborn for example. There the cultists also had an argument about how to ascend to the eldritch gods or even have proper communication with them. One faction tried messing with blood, another faction tried growing eyes on their brains for insight, and non of it worked properly, cultists are idiots in every setting, trying to comprehend what they cannot and dooming everyone around them to a horrible existence in the process.