Am only surmising but would think that even a landing that left the airplane inheritently intact on that reef would be rough enough as to cause some injury although she wrecked her plane before and walked away from it so whose to know.
Perhaps you have experience as a castaway on a Pacific atoll. I don't, but I do have some experience with the wildlife on Niku and I've never noticed any change in their behavior during the weeks that we spend on the island.
Not refuting your statement, have spent sometime on uninhabitated tropical Islands but with a means of transport so not as a castaway. We noticed the wildlife, mainly gulls and howler monkeys, but also other local wildlife would come right into camp with no fear until we showed aggression towards them to keep them away and then they kept their distance (of course when we left camp to do anything they had a field day, go figure)

I am "assuming" your crew had no reason to act with any aggression to keep the wildlife away so were still seen to not be perceived as a threat.
In my experience the wildlife will adapt real quickly depending on how you react towards them. As I have never been to Niku the species (hermit crabs excluded

) there may react differently then what I have experienced.
I think it's difficult to know how we would react to the stresses of being a castaway. Imagining how someone else might react is infinitely harder.
Expressing how I believe AE and FN would react which short of a hidden castaway dairy no one will ever really know.