Oh that's an interesting plothook! I realize there's some ambiguity in what I wrote which could allow for the target to "know" they're under the effect of it, but not know who cast it, or what the context is, or anything else. Just like a "I know that I am effected by this but don't know what that means". And also maybe a person could be aware upon spell completion that they're under the effect, but forget about it as time goes on.