I've noticed in a lot of HiEs (and I might be wrong) human suffering is downplayed too Pony suffering. I suspect this is because of the author and the high amount of hate they have within themselves. What do you think?

this sounds right to me.
i help with 1 or 3 of the five score story's and we try to split it across the board to balance the story out.

Usually when someone suffers or are in pain they try and express it any way they can and usually it ends up being through what they feel most comfortable.

In my primary HiE fic, Refined Starlight in a Broken vessel, the main character does tend towards melodrama and emphasizes a feeling that ponies would never understand his/human suffering, but that's more of a personal opinion of the character, one which multiple other characters point out as "unfair". Pain is fairly obtuse and so trying to equate one species' "pain" to that of another, especially such an alien one, isn't really comparable or contrastable at all.

I intentionally make my human characters suffer because I am vindictive. :)