This sucks... I'm sorry you had to go through this. The App Store review process is just pretty bad. It's especially frustrating when you see downright shitty apps on the store. The "black-box" aspect of it makes it that much more kafkaesque too.

When I first submitted my app on there, they rejected it and complained that I used HealthKit but didn't mention it in the app description. The thing is, I did. My app description had a list of "highlighted features", one them being "Apple health integration".

I was about to file an appeal, but then I saw a couple other apps with "Integrates with Apple Health" on its own line in the description. Figured that's probably what they were looking for (even though the guidelines don't explicitly say that) so I changed it and boom, the app was approved. I hate it, but it's not worth my time or the risk to fight it.

For what it's worth, I think your app looks really good!