Oh yeah I got that, I'm just saying I feel the narrative would benefit from those details being alluded to a bit more within the narrative itself instead of in a bonus "extras" thing that not everyone might read.
Definitely maintain the mystery and let players fill in the blanks, like you said, but I think it would help to leave a bit more of a bread crumb trail - maybe even just an extra throwaway line that alludes to the "incident" where Sarah expresses her fear that another "incident" is going to happen just like the last one. Again, leave the details open to interpretation, but give the readers a bit more to work with 😉
Keep in mind this is just my opinion and in no way objective or factual!