Well, the standard (?) model suggests vacuum energy doesn't change with acceleration, but that contradicts the Unruh effect. If particles are popping in and out of existence we expect some of them to acquire mass, even if they're short lived. Therefore there should be a "background curvature". You can try to relate that to the cosmological constant but Unruh says you see more of it when you accelerate, the temperature gets higher and thus the VEV must be changing. So, what is the relationship between the gravity of massive particles and the expansion of the universe? You see more expansion when you accelerate?As far as QM covering scales, the vacuum energy is one phenomenon which relates to all scales. It is in a dynamic equilibrium, but is also a stochastic process.