In my experience, it’s typically the transparent celluloids that are most likely to be a problem as the pigments used to make them opaque stabilzed the worst of the reactivity. You can really see this in action on the celluloid versions of tortoiseshell, where the razors will have rust spots in the shape of the transparent parts of the scales.

It gets complicated though because not all the transparent plastics that were used were celluloid. Some were lucite, some bakelite. Only celluloid scales are a problem.

While I don’t really think of the ‘french ivory’, or the opaque yellow, as being prone to acidic outgassing, it’s still certainly possible and I’d err on the side of caution and replace them.