Well, this is still not an actual explanation as to why you need it. I don't like introducing a new format, too. The current decTitleKeys.bin format is fine and easily readable for any software (for any human with a hex editor, too).
So... I assume you need those encrypted titleKeys, so that correct tickets (with encrypted, not decrypted titleKeys) can be generated? Is that the cause you need them? You can also just point me to a post that explains what you're doing with those encrypted titlekeys. But, please, give me an explanation. I won't add more features to D9 without clearly understanding their use (counting all, we have 111 features in there now already).
Also,
@cearp wrote that PlaiCDN does generated differing CIAs with the same title ID / decrypted titlekey combo. Is that correct and can you eloborate on that? I somewhat know the PlaiCDN code, so I'm wondering why that can happen.