reception. Is this serious? Real? Or just a fabrication?

Is this something real and authoritative and = worth investing time in?
(For example, like the Babylonian or Jerusalem Bible or the Tanakh or the books of Halacha)
Or is it just inventions like the books of sorcerers and there is no truth in it?

It's good that you don't have a question about the Bible. I would recommend that instead of wasting time on the Bible, you delve into occult literature. In my opinion, there are interesting mystical intuitions there. I don't see it as an invention, but rather as a commentary on other ways of looking at reality. Although I'm not sure it's worth spending time on the details.

Good luck.

Is there an accessible book about this?

I am not an expert, and certainly not in introductory books. There are many of them. The Ancient Keeper of Faith by Rabbi Irgas is the oldest and most well-known of them. But there are many contemporary books. Of course, each with his own method, but as mentioned, you should not be concerned with the question of who is right, but rather with the question of who is saying insights that speak to me and interest me.