Hopefully it's a phase and will pass.
Alfie goes through stages of regurgitating for me and sometimes he'll start as soon as I walk in and say good morning. I usually tend to tell him he's being silly and that I'll leave him to cool off for a few minutes and leave the room. I'm glad it's never got to the stage that Dorian has.
I have noticed that Alfie is now chewing a box then going inside it, which is new. Usually he just destroys the box and turns it into confetti from the outside. But the last few boxes he's been chewing holes then standing inside them. He doesn't seem to do anything inside, other than maybe chew them a bit more. And as soon as he catches me looking at him he runs back out.
Every bird is different. Timber doesn't pluck or anything like that when he goes through this. On the other hand, I can't say that others wouldn't. I think we just have do do everything we can, which you are already doing (limit touching, distractions, lack of nesting materials). It will pass!