I just posted another draft of a chapter from the Mandaean Book of John. In this chapter, chapter 76, there are a few places where the meaning of the text is not entirely clear (do I need to mention this when it is true of pretty much every section of every Mandaic text?). But the gist is that Anush-Uthra did works in Jerusalem that Christians claim Jesus did. This is blatantly polemical, and so it would obviously be a mistake to view this as in any sense pre-Christian, as opposed to being a late response to Christian claims.
I used “Christ” in my English translation because the Aramaic/Mandaic word mšiha in the text seems to be used as a way of designating Jesus, almost as a name, rather than in its more general meaning of “anointed one.”