Wow... I'm constantly visualising things. And often my brain will put together something I see in a strange way, so that for a split second I see something for what it most certainly isn't. So yesterday, I was looking at a tree and I saw a panda, because of the way the leaves were arranged and with the dark background because it was dark outside but there was street lighting so I could see the leaves. But of course it wasn't a panda. I've also mistaken someone's bag for a shetland pony before, I think that was because of how the bag was interacting with other things.
Sorry this is the complete opposite of what you are talking about. I am not too good at visualising faces, so I try to remember what people are wearing and their hair colour instead if I'm looking for them in a shop. But again, that's visualising. I might have to conclude that I can't visualise not being able to visualise, and I'm sure that's not very helpful, and I should maybe delete this post but I'm trying to censor myself less.
It sounds like she will be able to cope, and now you know she has this problem you can understand and support her with coping strategies; maybe pictures to carry round might help?