I read back through the thread. I think the problem started when sand was brought in to build up the pool site. Even though the pool was taken down, it says some of the sand was scrapped off and decomposed granite brought in to level the pad. All of the sand should have been removed, the lowest spot identified and used as a reference to level the site. You have to dig down to undisturbed earth since, as you can now see, nothing is going to compact the earth as well as the weight of the pool. Water weighs 8.34 pounds per gallon. When the second person came in to level the site, they built on top of uncompactable sand. Since the site wasn't firm and level to begin with, when decomposed granite was added it just compacted down into the soft, built up areas once the weight of the pool was on it. This may also have caused the problem with the bottom rail being out of round.
Keep an eye on the pool by taking a picture of the same spot every day for four weeks. You have a photo showing how one of the posts is not plumb vertically. Mark on the paver where post should rest if the wall was vertical. Use a different colored marker to show where the post is on that date, and once a week check to see if the post has moved. If you are seeing movement then you should take the pool down immediately. If there is no movement you can wait until the end of swim season to fix the pool. In my opinion this pool should be taken down and the site properly leveled on undisturbed soil. If you want to do this yourself, you can make a water level. To make sure a site is level start where the lowest point was identified and use that paver as the reference point. I'll edit this post to include some drawings to clarify the instructions.