Since you talked about Featherine as a witch, I’ll talk a bit about Ikuko as a human. Staving off boredom is I believe also Ikuko’s reason for writing stories, or at least it was until Tohya arrived. To me it seems clear that writing the stories was a therapy of sorts for Tohya, a way to deal with his memories of Battler. But it was something different for Ikuko.
It’s not until episode 6 that she directly inserts herself in the story, and not until much later that she involves herself with Battler. Episode 6 is Battler’s time to prove he understands the truth. Tohya has completed his journey through Battler’s memories to understand the events of Rokkenjima and the nature of Yasu. So Ikuko takes on the role of an observer for his answer, but also as a guide for Ange.
Featherine is often cruel to Ange in the story, usually through Bernkastel as her proxy. She does seem to be guiding Ange on her journey but in a different way than Battler. I think this is a fundamental difference in how Ikuko and Tohya think Ange should approach the truth. Tohya doesn’t think the truth is important for her, especially when it cannot be proven, what is important is the future. Ikuko thinks Ange should face the harsh reality of what happened, even if it is not 100% guaranteed to be the real truth. Tohya’s stance seems to be based on his memories as Battler making him take a softer approach. Ikuko’s approach seems more like a tough love.
But I think there is possibly another motive. Ikuko wants to protect Tohya from Ange. We know Tohya turned her away when she tried to meet with them because he was afraid that Battler would replace him. Ikuko probably fears this as well and wants crush Ange’s hope that Battler will return and end her search for the truth so that the risk of her meeting with Tohya goes away.
Ikuko’s actions with the witch hunters also show this kind of sentiment. She brings them all together to shame them about the way they act. The effect this will have is to decrease the mania over the events of Rokkenjima which would in theory provide stability to both Ange and Tohya. The less people clamoring over the truth the less she has to worry about anyone learning Tohya’s secret and the less Ange will be driven to investigate it herself.
That was a bit more rambly then my comment usually are, but it’s nearly 1AM I should go to sleep.