The backwall with lots of texture reminds me of tree bark, just an observation. I do feel like the textured wall runs the risk of conflicting visually with actors (player/foes/items) by creating a lot of visual noise.
If you use something more akin to the plainer backwall, then you could add occasional terrain backwall. Maybe a large crack, tunnel entrance, cave painting, under emphasized rock in the wall, etc. I think this could help a cave environment be more memorable and navigable.