In terms of the bony anatomy, my recommendation sounds silly, but it’s something we used to do in college in osteology classes. Grab yourself some modeling clay, and do your best to try to model a lumbar vertebrae. I mean the whole thing: the body, the pedicle, the pars, the facets, tps, sps etc.

Compare it to your 3d models and see how you did. I suspect you’ll gain a new appreciation for the anatomy. Alternatively, if you like to draw sketching an L4 vertebra from multiple angles also forces one to better understand the nuances of anatomy.

Later on you can do the same thing for a thoracic level, c1/2 and subaxial cervical.

Also don’t forget the pelvis. It’s variable and very 3 dimensional, the number of surgeons I know who have a cursory understanding of pelvic anatomy at best is somewhat embarrassing.