The inspector and your agent should share the blame of lack of service to you. They should know better and advise you the extent of issue, in a worst case.
No more advice on litigation. As far as mitigation of your problem, you may need structually repair the concrete wall in the swimming pool before re-tiling the surface. You need to make sure that any leaking of the pool water does not flood the foundation of your house that cause settlement/cracking of your roof (clay tile?)
You need have some structural engineer to inspect for signs of settlement, a potential cause of foundation settlement for any reason. Teh buyer/seller building inspector is NOT up to the job. A contractor may be biased for a fear-sale practice to exaggerate the issue.
BTW, hope you get earthquake insurace in your policy.