I have found a way to remove the enderman glowing eyes, but you will need to COPY (Don't delete) the enderman eye file from the original textures(which can be found under assets, look for textures and click on entity, then open enderman folder.) , edit the texture to remove the eye texture. And add it to the enderman folder in the downloaded pack. And the glowing should be gone.

Adjust the eyes a bit, lower them,it looks a bit wonky