What immediately jumps out at me are your statements that there is "no clear learning" happening, accompanied by a lack of ownership and accountability.
(Is there something ironic about "accountants" lacking "account-ability"?)
Mistakes happen. As Einstein once said, "Anyone who has never made a mistake, has never tried anything new." So that's a given. But you hit the nail on the head by recognizing that your organization is not LEARNING from its mistakes. When that happens, not only is it a missed opportunity, but you are doomed to keep repeating those mistakes. And that can only go on for so long before the business is driven into the ground.
To become a "learning organization" and to create a "learning culture" requires seeing EVERY experience as a learning opportunity and viewing every win or loss as a teachable moment. This entails analyzing "wins" to see what worked, and dissecting "losses" to see what didn't. Sweeping mistakes under the rug and pretending they didn't happen -- or, even worse, finger-pointing and blaming others for the mistakes -- is a missed opportunity, and creates a toxic environment.
As Edison said, "I didn't fail 10,000 times; I learned 10,000 ways how NOT to make a light bulb." Similarly, you need to, as an organization, sit down and figure out what's working...and what's not. And start making some real changes.
Explaining how to create a learning organization would take up far more space than I am allotted here, but it entails creating a culture of openness, honesty, authenticity, transparency, and trust. It's about creating an environment where open dialogue can take place without fear or blame, where intelligent risk-taking is encouraged, and where innovation can flourish.
Easier said than done, but it can be done if everyone is committed to making it happen.