OK they weren't the best example, but for the record non-flammable paper is not actually non-flammable, it just doesn't sustain combustion because of a chemical in the paper. Austenitic steel is not iron, it's iron + carbon.
As long as you have two metal end caps connected by metal poles, and you lay the carbon fiber in the direction that connects the end caps, then it seems that the hull would become concave/"bulge inward" and the fiber would hold pressure by tension.
Not sure whether this would actually work in practice though or whether it would be better than the simple metal sphere design.
These exist, but are not common.
> "non-magnetic iron"
Austenitic stainless steels are a thing.
https://en.wikipedia.org/wiki/Austenite
So I'm not sure if I like those examples. It's more along the lines of using baked clay under tension, or a rope under compression.