Thanks, Massimo. It looks like I have forgotten about that difference, so thank you for reminding it to me!

I totally agree with your interpretation regarding having no plan designed for passively accepted risks. So I would also expect that—should one of those risks arise—you as the PM would need to implement a workaround. As workarounds are not planned in advance, though, I would expect management reserves to be used, which brings me back to your point, I guess.
I'm sorry I couldn't be more help in there, but it truly is an interesting (and intricate) question!
Gabriella