Will BBL or butt augmentation help with uneven buttocks due to scoliosis? (Photo)

Yes, fat transfer and liposuction techniques can be used by an expert to improve these aspects.  Liposuction of the abdomen, sides, lower back, and bra rolls with fat transfer to the buttocks and hips should produce the best result for you.

Thank you for your question. Based on your photos you appear to be a good candidate for this procedure, but it is recommend it to have in person evaluation with a board certified plastic surgeon with experience in this procedure, to get the best desired results.
Respectfully,Dr. Emmanuel Mallol Cotes.-

With scoliosis, your pelvis may tilt differently from side to side, which can also contribute to your overall appearance. A BBL may help better balance the two sides as well.

Liposuction and fat grafting can certainly provide more balance to your frame.  Your primary issue is your hip discrepancy rather than the buttocks.