My situation isn't exactly like yours, but maybe what I've observed will help. I am also a novice and this is my first build and Hackintosh as well, and like you, it has worked extremely well!
I had sleep set to 10 minutes. Prevent computer from sleeping automatically when display is off is not checked. Wake for network access is not checked (if checked I think it would never go to sleep but I need to test that more). I have this YOUBO Bluetooth/Network card from Amazon
https://www.amazon.com/gp/product/B082X8MBMD/?tag=tonymacx86com-20
which when I opened the box is a Fenvi card, but it doesn't look like the picture of the Fenvi T-919 card on amazon so not sure what the difference is.
What I noticed was that after 10 minutes the display and computer would in fact go to sleep but immediately wake again (not the same situation as you). This continued to happen at night but in the morning when I woke up the computer and display were asleep. Others had reported problems with the bluetooth cards causing sleep/wake problems so I tried some tests.
1. I turned the keyboard off. After 10 minutes the same thing happened, the display and computer would sleep then immediately turn back on.
2. I turned the mouse off. After 10 minutes the display and computer went to sleep and didn't wake up. I'm using an Apple wireless keyboard and an Apple wireless mouse.
I thought that maybe when the computer went to sleep that the mouse was not being told to sleep and it would rewake the computer, but the mouse would eventually go to sleep itself and that was why I would find the computer asleep in the morning.
I wasn't sure how long it would take the mouse to sleep on its on, so I tried increasing the sleep time to 30 minutes. Now when the display and computer go to sleep, they stay asleep.
This is only speculation, but I suspect that the mouse is not being told to go to sleep (for whatever reason) and it stays awake for some period of time before it itself goes to sleep (as long as it is not touched). Being awake the mouse causes the computer to immediately wake from sleep until the mouse goes to sleep.
I followed Casey's instructions to the letter and have not made any modifications that were not specified in his instructions. I'm using an Intel i9-10900k CPU, a Sapphire RX 5700 XT video card, two NVM's for disk, two hard drives for backups, 64GB memory. If you want more detail, just let me know.
Don't know that any of this will help, but hope you find a solution.
Rand