The underlying idea you have is that the artificial CSAM is a viable substitute good - i.e. that pedophiles will use that instead of actually offending and hurting children. This isn't borne out by the scientific evidence; instead of dissuading pedophiles from offending it just trains them to offend more.
This is opposite of what we thought we learned from the debate about violent video games, where we said stuff like "video games don't turn people violent because people can tell fiction from reality". This was the wrong lesson. People confuse the two all the time; it's actually a huge problem in criminal justice. CSI taught juries to expect infallible forensic sci-fi tech, Perry Mason taught juries to expect dramatic confessions, etc. In fact, they literally call it the Perry Mason effect.
The reason why video games don't turn people violent is because video game violence maps poorly onto the real thing. When I break someone's spine in Mortal Kombat, I input a button combination and get a dramatic, slow-motion X-ray view of every god damned bone in my opponent's back breaking. When I shoot someone in Call of Duty, I pull my controller's trigger and get a satisfyingly bassy gun sound and a well-choreographed death animation out of my opponent. In real life, you can't do any of that by just pressing a few buttons, and violence isn't nearly that sexy.
You know what is that sexy in real life? Sex. Specifically, the whole point of porn is to, well, simulate sex. You absolutely do feel the same feelings consuming porn as you do actually engaging in sex. This is why therapists who work with actual pedophiles tell them to avoid fantasizing about offending, rather than to find CSAM as a substitute.