Can you try to describe the "localization" you're hearing? Localization is usually caused by hearing frequencies above about 80 to 100. It is manifested as hearing sounds "attached to" or "emanating from" the subwoofer. Often it's deep male voices where the fundamental frequency of the voice falls into that range. Darth Vader's voice comes to mind. If you are hearing his kind of directionality of specific sounds, that can usually be corrected with a lowering of the crossover. What crossover are you currently using? Also, what subs are you using? (Sorry, I forget.)
Another thing you can try is changing the closer subs' Distance setting. If your version of Audyssey has SubEQ2, you can set different Distances for one sub output than the other. The "Precedence Effect" states that directionality is determined by the first arriving sound, even if the later arriving sound is louder. Therefore, try adding a foot or 2 to the rear subs, effectively delaying them 10 or 20 ms. The front subs will arrive first and define the directionality and the rear subs will arrive later and add volume. However, be careful as these types of changes can also impact the FR. (Disclaimer: The Precedence Effect, or Haas Effect is usually defined with midrange frequencies. I'm not sure how low in frequency it applies, so don't take this as gospel.)
OTOH, if you a just "sensing" that all the bass is coming from behind, that is a different issue and it won't be corrected with a crossover change. Lowering the levels of the rear subs might help, but remember that you can run into issues with headroom if you use different trim settings or gain settings for one or more of the subs. Nonetheless, that may be a worthwhile tradeoff if it works.
I have 3 subs placed around my room at different distances to the LP, and I'm using a 100 Hz crossover on all my speakers. They're all 3 gain-matched, (using the AVS common definition of gain-matching.) I don't hear any one of my subs more prominently than any other sub. They all blend together and provide just one big bass response.
Lombardi said it:
Perfection is not attainable, but if we chase perfection we can catch excellence."