Well, you can finish it as it is not a game-breaking bug. You just have to avoid using Scrying and Revelation Quill and Eagle. Augury works fine. Admitedly, the last scenario almost needs as much scrying as you can to get the terrible runelord to the bottom...
Unfortunately, the bug will be with us for a very long time, possibly forever
Thanks for the reply. I eventually was able to beat it on normal difficulty by hoarding Augury spells and using Shalelu Andosana. Not sure how the higher difficulty levels will shake out.