Yes, they are consistent. In fact, they are the result of the following line of thinking: given that we are observing unexpected results once we account for (us

Yes, they are consistent. In fact, they are the result of the following line of thinking: given that we are observing unexpected results once we account for (using the GR paradigm) all the clearly apparent mass and energy, what else could we change so that GR doesn't have to change? In other words, the consistency with GR is already baked in. That's not to say that the approach doesn't have huge merit. One model for dark energy is indeed the cosmological constant, but there are other approaches, most notably quintessence (https://en.wikipedia.org/wiki/Quintessence_(physics) https://en.wikipedia.org/wiki/Quintessence_(physics)).