that's gacha logic to be precise, but that aside the mc advantage of hell mode is kingprotea's ability of infinite growth, in other words no lv cap while having exp reduce 100 times making others having a 100 times exp growth but supposedly with lv cap
I don't really consider her a Mary Sue. She might be at this point, but at the beginning of the story she struggled quite a bit as a maid. Yes, she's awesome now due to the dreams she's having, but those dreams add to the mystery of the story more than make her a Mary Sue. Why is she having these dreams? Who is sending them to her? There's more to it than "she's awesome because."
All we know is he's a transvestite, which means dressing stereotypically female when you're not. We have no idea what his sexual preference is, he might be homosexual but it's also entirely possible he's not. He could be bi, or pan, or straight or even ace for all we know. He might even be a eunuch, it seems unlikely but there were Chinese eunuchs back in historical times and he may be one of those if he hails from those times or one of those traditions.