The thing is, it's not just a vision of something that believably might happen. What the Winter Queen showed Ara'lon was the end result of something that was already happening. The death and destruction of Ardenweald was in-progress, and clearly visible all around them. It's not just what the Winter Queen thinks is going to happen. She's more than likely better attuned to the state and health of her own realm than literally anyone else in the Shadowlands. Ardenweald is dying and she knows it clearly.
I don't see your point here. What she saw was a vision of the future in which nothing was done to stop it. So of course she didn't foresee the aid of the Maw Walker. I don't understand where the fault lies with the Winter Queen here. If she'd seen the ordained future that was destined to happen with the aid of the Maw Walker, then the presumption is that steps still need to actively be taken to keep Ardenweald alive so that the good future can come to pass, which still means sacrificing slumbering souls to use their anima to slow the death of the realm.
What... What's the problem here, exactly?