Withers was able to fix things after all.
Did a respec to a different class just to get right away from wizard spells and then back to wizard and even though the spells were already in my book it gave them option to choose some of them again and reach level 10.
That's great! Well, perhaps not great, as obviously there's still a defect, and also I can imagine it would be confusing for people respeccing that they can end up selecting spells they already have. But at least it's good it works that way currently so you have a workaround to finish your game, while hopefully a proper fix will be along at some point.