For the possible future update plans of Har-Bal, I would like to propose one thing: Har-Bal might have M/S (mid-side) processing capability. For instance, a stereo mix can be analyzed and converted into its M/S components inside the Har-Bal. Then we can harbalize those two sections independently...

Let’s say we have a mix whose low-mid (or any) frequencies in the M (mid) region could be manipulated without affecting the similar frquency content existing in the S (side) region. Perhaps there could be two dedicated Har-Bal windows one of them is used to EQ the M component, and the other one can be used to EQ the S component. Since these filtering processes do not affect each other, it would give the mastering engineer further flexibility, and probably obtain even better results with the power of Har-Bal. It would be really even more fantastic mastering EQ...
Cheers
Kursat