Not even sure If envato allows you to write about other marketplaces here … just write me a pm/mail if you still want to know it.
Regarding your flyer:
I dont really have experience with that category but the overall quality and design looks fine for me.
Maybe too many similar halloween flyers ? Some problems with the bleeds ? Missing model release ?
Well, we never know, since we simply get no feedback at all.
If you have to carefully check every file, which I hope they even do, why is it too mich effort to write one single sentence about the reason for rejection.