Then the subwoofer crossover is too high, or not steep enough. If you can still locate the subwoofer at 80Hz with a 12dB per octave slope, that is impressive, and at 60Hz that would definitely fall into mutant territory.
Once you have both subwoofers playing together in mono, they should sound better than being in a stereo config.
Not really, if the subwoofers are not close to the speakers or at the same wall/corner they’re still localizable.
stereo subbass is stupid though indeed. I would definitely turn it to mono by having both Dirac inputs go to each of them.