Aren't coatings only on the outside of the front element ? Since most of the fungus I encounter is usually on the internal glass, there isn't any coating to get damaged ....?
From what I've read there are different 'breeds' of fungus - some more aggressive than others. I guess it depends how long it's been in contact with the glass aswell. I also read that even when the glass has been cleaned there are still spores lurking inside the lens body and workings which can re infest.
Thanks for all the info