I agree that in general for most people liposomal is probably not too much better.
However for some people it seems to really be better, especially a quality brand.
And with such a severe illness like addison's you really don't want to impose any limitations on potential healing success.
I would not back off at all on vit. c, take as much as you can handle no matter how high the dose. Or perhaps stagger the dosing to every hour or two. Maybe also look into a good quality buffered C or a brand that includes flavonoids.
Liposomal might* enable you to take more, or tolerate similar doses without it irritating the gut. You can make your own with a some simple tools - google.
I would try to look into food sources for good quality C like amla, or acerola cherry powder. Isolated vitamins are usually not as good as whole foods.
Add organic raw egg yolks and salmon oil to what I posted earlier.