cg_shadows 3 was fixed in the OpenGL2 renderer a few months ago. cg_shadows 2 is still broken.
The OpenGL2 renderer also has cg_shadows 4 which is somewhat glitchy shadow map projection shadows similar to cg_shadows 2/3. Shadows cast from the sun that can be enabled using r_forceSun 1. However r_forceSun is cheat protected so you have to load map using the