Minecraft shaders is a lot of post-processing, volumetric rays, and haze to make it more pleasing to look at. Mine-imator has basic post processing effects, but not like shaders.
To my knowledge, shaders use real AO instead of screen-space ambient occlusion, which is one of the reasons why Mine-imator’s lighting can look glitchy at times.
light rays are coming to Mine-imator 1.3 in 2021, along with a load of lighting improvements which will make it much easier to achieve a shader-look.
TL;DR Mine-imator was made in the wrong engine and it’s a miracle of coding that Mine-imator even comes close to shaders at all, and 1.3 will greatly enhance your lighting.