We explore the potential resolution of the so-called dark universe conundrum via the unification of the cosmological dark components, namely, dark matter (DM) and dark energy (DE), from a semi-classical fluid description of a Bose–Einstein condensate (BEC) of light bosons. Specifically, such a unification, which implies the same fundamental origin of DM and DE, has indeed been shown to be accountable from the BEC energy density, identified with the corresponding probability density, whereas the associated (Bohmian) quantum potential can account for the DE density semi-classically. The ‘macroscopic’ BEC wave-function can be chosen such that the BEC energy density resembles that of a CDM. Nevertheless, as illustrated in some of our earlier works, neither the BEC density equals the total effective CDM density, nor the quantum potential equals the total DE density, as the entire bulk of the universe contents (including the visible baryons) back-reacts on the metric structure of space–time due to the quantum-corrected Raychaudhuri–Friedmann equations. Such a quantum back-reaction crucially constrains the BEC mass, wherefrom one can infer that the BEC acts almost as an axion-like scalar field DE, rather than as a DM! However, in those works the inhomogeneous part of the BEC density has been ignored, at large scales, taking the view that it would not affect the background cosmological evolution. Examining the effect of this inhomogeneous part on large-scale cosmology of course requires standard techniques of averaging of inhomogeneities over a suitably chosen domain. The latter may conceivably be much lesser than the spread of a Gaussian, which can serve as the BEC wave-function, as shown in the earlier works. We carry out the averaging here and show that, despite having corrections to the cosmological solution obtained earlier, the BEC mass bound from the quantum back-reaction remains intact, and so does the above inference.