5 months post-op I've had butt dents since around 2-3 months. Could Sculptra or a non-surgical fix help? (photos)

There are several ways to address cellulite depending upon depth of cellulite, location, elasticity of overall skin envelope, and subcutaneous fat layer.
There is no uniformly successful method for treating it.  My practice is now using BodyTite, a non-invasive procedure, that requires no down time to reduce the appearance of cellulite. 
The procedure combines different clinically proven modalities (radio frequency energy, deep tissue heating and suction coupled negative pressure) to distribute heat to the skin and underlying fat, causing the tissues to contract. Weekly sessions over an eight week period are recommended, but improvement is likely seen after the first few sessions.
Kenneth Hughes, MD, ABPS Board Certified Plastic Surgeon
Los Angeles, CA

It appears from your photos that you have cellulite, which is very common and tends to get worse over time as we age and or gain weight. There is a large genetic component to cellulite so some patients have it worse than others. A BBL does not correct or treat cellulite. Immediately post op due to swelling things look very smooth and shiny. After things start to shrink and settle, these superficial irregularities tend to surface. Sculptra can definitely help! 

The definitive correction for liposuction deformities requires the advanced technology of ultrasound assisted VASER liposuction. As an official trainer of VASER liposuction, I encounter suboptimal liposuction outcome referrals weekly. VASER liposuction has been the only modality that has consistently corrected liposuction caused deformities. VASER liposuction ensures a smooth contour regardless of severity of contour irregularities by virtue of being able to remove any and all remaining fat comprehensively and uniformly. Finally, when skin redundancy irregularities are observed, Renuvion technology can be simultaneously applied to tighten your skin to optimize your overall contour outcome. A Skype or FaceTime consultation with a VASER specialist will help you get an accurate recommendation and pricing.
Respectfully,
Arian Mowlavi MD, FACS
Realself 100 Hall of Fame Inductee

The contour irregularities are cellulite.  This can become worse after adding volume such as a BBL or weight gain.  Cellulite is formed from connective tissue bands that anchor the skin to the underlying muscle fascia.  These bands are not very pliable and don't stretch much. When volume decided they create an indentation.  The most effective treatment for this is  subcision with a device called Celfina. This done in combination with adding either fillers or fat is the most effective.  Fillers alone or adding more fat will most likely not correct this.  Best, Mats Hagstrom MD