Good luck with this project
I'd agree with @nobody. The pics are ok but you definitely need heavy pixel art intervention to clean those up (if your goal is for an AAA result that is). Plus some better palette usage. If done properly even 32 colors are perfectly fine (you could also use EHB mode which could offer you an extra 32 color shadows palette with little performance overhead).
Some tips for converting 3d gfx:
-For backgrounds/tiles make sure all your exports have zero dithering. Clean, unified and single color surfaces are hugely much preffered than a dither fest. After the first exports, if you still want dithering you can add some manually (but as a rule of thumb it's better not to overdo this imho).
-Same for bobs/sprites, export with zero dithering. Apply manually later where needed. Also make sure anti-aliasing around your shapes is off (if possible). This will definitely require some manual work later to fix the details.
Having said that, I also agree with Akira on his points.