A Problem motivates what the cast wants to achieve, but it is not the achievement itself. In this case the Theory book is describing the Goal: how the protagonist hopes to counter the central inequity.
I asked @chuntley about this very issue and he responded:
“The story solution resolves the inequity driving the Overall Story throughline. This is independent of whether or not the Goal has been achieved.”
I think this allows for the Goal to be “wrong,” per se. In How to Train Your Dragon, the vikings learn to accept dragons as comrades (OS Solution - Acceptance). But the original goal of “training the next generation of dragon killers” does not succeed – the young vikings become dragon riders instead (Outcome - Failure). The inequity is resolved, practically in spite of the Goal.