The cloud-digging idea is genuinely fantastic, and you have great painting skills on that cloud! To fix the disconnect, I would recommend adding some soft shading and highlights to the lizards so they have the same 3D volume as the clouds. Even a simple drop-shadow underneath each lizard where it touches the cloud would instantly make them feel like they are actually landing on or burrowing into the surface, rather than floating on top of it.
Other than that, I really love the concept of creatures that 'swim' through clouds; that's a very creative and playful take on the sky island theme.