(note that DE cannot explain the UA).
Why?
I should be clear that when I say DE, I mean DE as understood by mainstream cosmologists.
In FET, the UA is the acceleration of the Earth
through spacetime, which is why we feel acceleration. In RET, DE is driving the expansion of spacetime itself. So, if there was a huge concentration of DE beneath the Earth, all this would mean is that spacetime below the Earth was expanding rapidly, but the Earth would remain locally at rest, and so feel no acceleration.
This setup would be
roughly similar to the hypothetical
Alcubierre Warp Drive, in which an object can be accelerated to past light-speed w.r.t. an external observor, but locally remains at rest and feels no acceleration.
Therefore, DE cannot explain the acceleration we feel.