If you get off track, you can get back on track when you try to read The Necromancy of Thay. If you give it to Gale, the next long rest will be him absorbing the Weave of the book, and then you can give him artefacts even if you missed go to hell, mirror image, and asking for artefacts. Then assuming you have high enough approval with Gale, you will eventually get "the weave" and "lost Mystra" scenes. These only trigger if no one else, including the dog and the owlbear, have anything new to say.
