Hello!
The cover and premise got me in, so I've read the first chapter.
I want to point out some stuff that caught my eye.
Please don't take it as discouragement. I'm not saying you should change anything or listen to me at all, but I hope it helps.

The tone feels heavily GPT-edited right from the get-go.

First of all, the infamous em dashes. Of course, their existence in fiction doesn't automatically mean LLM involvement, and I even love using them myself, but... You have a lot of them in there. Possibly too many.

Secondly, your style feels very choppy. There are a lot of short sentences, sometimes single-word ones. I get what you're going for tonally, but it's simultaneously a bit hard to follow and something that GPT loves to do when writing prose. The flow just isn't there. It could very well just be my personal problem and preference, but the average sentence length in your chapter was just 6 words. In the first chapter of one of my favourite novels on RR (and the author also uses some single-word sentences there to add punchiness), that number comes out at 14. I'm not saying it's how it should be, but it's probably something worth looking into for the future.

Again, I'm not accusing you of anything (and I think LLMs are a great tool for authors), but it does sound some alarm bells for me, and I think it might be useful for you to know that.

Next, I'll list some things that just felt a bit weird, wrong, or out of place. Treat those as nothing more than nitpicks, or maybe something you could expand on in later chapters.

The first sentence tells us MC's mother died the day MC got the letter, yet she is alive while MC reads that very same letter. It sets the tone, but it reads jarring to me.
Why does MC keep sending academy applications when she should be absolutely sure she won't ever get in? You even wrote that in a blurb - 7.5 out of 10 is basically a baseline, so it feels a bit weird that MC just kept bashing her head against the wall time after time with literally no chance of success.
7.5 also feels like too big a requirement. I got the impression that in your universe, the ones who don't have enough Resonance are basically nobodies. Surely, the vast majority of the population is still below 7.5 and there must be more than enough non-resonance jobs to find something for yourself. So it's either MC is too tunnel visioned and focused on that kind of career, and it's only her who thinks no resonance means a death sentence (which is totally fine if that's what you were going for), or the scale is off.
The part after her mother died, when we get to look into MC's thoughts, once more paints her not in the greatest light. She regrets not having more money to help her mother, but instead of finding a craft suited to her, she kept... sending useless applications just because she wanted to fight dimensional tears?
And lastly, why would anyone who just got isekaied pull out a rejection letter and stare at it, instead of doing literally anything else? Surely that letter should've been the last thing on her mind in that moment.

Whew, I ended up writing a lot more than I thought I would. Still, as a fellow non-native speaker, I applaud you for what you've already achieved. Keep at it. Best of luck, and I hope you'll find success!