Older Narrative Style (like older fairy tales)

I'm struggling to understand what you mean, could you give an example?

I think you can do almost anything you want for this competition (within the bounds of age appropriate, no swearing and keeping it scifi or fantasy).

That being said, they're trying to create a volume that is intrinsically interesting. If you write a trope - like werewolves or fairytale-esque then those are so old, and been done so many times, and the judges will have read versions of it so many times and have read the very best versions of those kinds of stories, its probably a harder thing to get into the finalist circle. Unless you write the absolute best version they've ever seen.

The other thing to consider is this is aimed at middle school, so at that age were you reading fairytales? My kids didnt. I tend to think of it as something we read to much younger kids, and things we come back to when we ourselves are older. Thats just my one experience having raised two boys - but it will depend on the content and tone of your stories whether it feels right for the age group or not and not having read your pieces its hard for me to guess if thats the issue

I struggle to read some of the stories you mentioned. To me, they often read like a list of things that happened, rather than a story that evokes emotion. They also do that in a very wordy way. Is that the kind of narrative style you're using? If so, it might come across as dated? I imagine there are masters that can do it successfully, but if we're entering WotF, we're still honing our craft.

The opening of The Golden Bird, for example:

A certain king had a beautiful garden, and in the garden stood a tree which bore golden apples. These apples were always counted, and about the time when they began to grow ripe it was found that every night one of them was gone. The king became very angry at this, and ordered the gardener to keep watch all night under the tree.

And so it continues, wherever I dip into the story. I don't know if it's the specific translation, but it's awkward to read in places:

Before the castle gate all was as the fox had said: so the son went in and found the chamber where the golden bird hung in a wooden cage, and below stood the golden cage, and the three golden apples that had been lost were lying close by it.

There are loads of short story anthologies that put modern spins on fairytales that work really well, so it can be done. More concise writing, senses/feeling, and largely avoiding passive voice.