Thanks for this simicrintz.
I was under the impression of the opposite. I thought that if this wall decides to start to crack again, I would be better off seeing it and fixing it with epoxy injection before it gets too bad. If it starts to crack behind the liner, even if I can feel it, I would have to remove the liner to fix it. This would scrap the liner.
When the pool was originally installed, there was at least three feet thick by the depth of the pool of sand around three sides of the pool. The fourth side(the one that cracked) only got 8 inches of sand and the rest is extremely hard soil. I plan on refilling all sides with healthy amounts of appropriate sand and a french drain in 12 inches of gravel at the four foot deep point. I've also removed the mature tree that was three feet from the crack, along with all it's roots.
All that to say, cross my fingers, I hope that this repair is good for a long time.