Part of the reason I'm confused is that, the radiant barrier type of bubble wrap used here, has foil on both sides.
Radiant Barrier (bubble wrap) does not have an R-value because it's intended purpose is to slow radiant heat and is not intended to reduce conducted heat. Although it may actually have a low R-value, R-values apply to conducted heat and would be misleading when comparing radiant barriers. The air gap that is mentioned in your link is intended to separate the the radiant barrier from the regular insulation. The radiant barrier is still a vapor barrier, so it needs to be directly against the metal. Then an air gap, then the fiberglass insulation or foam panels can be used.
So, having said all of that, in my home, I would do this.
On top of your perlins, nail plates, lathes, whatever the lang is in your area, put the radiant barrier on top. Then fasten the metal directly on the radiant barrier (bubble wrap).
If you want to insulate the ceiling for an R-value, I'd put foam panels under the lathes, or perlins, or nail plates, or whatever you want to call them.
More insulation? Put in a ceiling and insulate with fiberglass. Leave the bubble wrap against the metal.
If there is a foil face only on one side, I'd turn it away from the metal. Where the vapor barrier should be.
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