Hi, reviewing this for the WA Special Places Challenge.

Your opening is great; engaging and really showing why the Fertile Holding is so important to Nailah. ( boar hunting, "wood piles indicated where they'd been a fire," etc.) At the same time, this isn't just a cute little garden. It's a dangerous place, where not all people survive. ("Wild predators and unpredictable herds of beasts roamed freely,")
Still Nailah loves it, and that is summed up well in this sentence, "To Nailah, this place was a veritable paradise."

That brings up the huge conflict when her twin brother wants to enter the trials, and therefore, leave the Fertile Holding. Should she stay in the place where she feels most at home, or go with the person she loves the most who depends on her?

There is no easy answer and I think showing so much of that conflict "off screen" (the fight between her and her brother, and even her final decision) works to your advantage. Most people would say such dramatic moments and in many ways, "climatic moments" should always be shown.
But here, the issues are so complicated, I think it does better to imply them, and have the reader interpret how they happened.

The final scene is so bittersweet. Nailah does compete in the trials with her brother, and returns to the Fertile Holding. But it's been so long, it doesn't feel like home anymore. :(

So typical of "special places" that we have when we are young. When we finally return, they don't feel the same.

Overall, this is a good story that fits in well with the new challenge at WA.

I did spot a few possible errors:

I'd wager they got to confident here.
Wrong type of to used there, probably should be this:
I'd wager they got too confident here.

I can’t help thinking this should be two sentences (missing a period.)
Nakth says there is a pack of manticores having a fit I think two packs are fighting for territory.
Nakth says there is a pack of manticores having a fit. I think two packs are fighting for territory.

Just a little awkward:

How many of them made it, you think?

Possible corrections:

How many of them made it? What do you think?

Or

How many of them do you think made it?

Others doesn’t need to be pluralized:
As they got closer, they saw the others viziers bowing.

As they got closer, they saw the other viziers bowing.

Feels like there is a word missing here:
She could not imagine letting him go the trials alone while she stayed here.

She could not imagine letting him go to the trials alone while she stayed here.

or

She could not imagine letting him go through the trials alone while she stayed here.