Yes, it can be done, there are even tools to humanize ai generated content as you can see in the next image
They don't work, or at least they didn't. Some time ago,
when I saw these humanizers advertised, I tried a couple of them and they were detected. Also, the fact that you got caught makes me think they don't work as well as you say. I'm not going to bother to see if they have improved but it seems to me that this is going to be like plagiarism with the internet: when it emerged it made plagiarism easier, but anti-plagiarism tools that detect it also emerged.
I don't quite buy your story because of several things that have been mentioned: you have done the alleged experiment with your main account, with the one you charge for signature campaign, and without telling anyone, neither the mods, nor your campaign manager or anything else. You could even have signed a message with a known bitcoin address on the forum saying that this was an experiment before you started.
Now, I don't agree with someone like you who has been on the forum for 11 years, using AI for 6 days and being called an AI spammer.