OK, so the first thing I would do is to make a copy of your existing .aup3 file, just in case anything you do in the future breaks something.
I believe you have found the right references. The first thing I would to is repeat your copy-paste the entire project to a new project, copying selected audio only. If this gives you problems, limit the copy to a few tracks at a time, then merge the copied tracks later on. I don’t know why the audio data size is so large - this is obviously a glitch of some kind.
So we know that your project is damaged. If you are unable to copy all of the tracks out, you are going to have to repair the project. To do this you will need access to a Windows machine. See: Corrupt or Otherwise Broken Audacity Project Recovery
Next I would get rid of the envelope control points on the copied database (back it up first). I don’t think you are going to get the error that you got before, but if you get the error on a repaired file post back.
Come to think of it, post back either way.