Claudia Kim's character in Fantastic Beasts: The Crimes of Grindelwald has been included in all marketing material and trailers for the movie so far, and yet her character is only billed as Maledictus. The lack of a name when everybody else has a full title could either be because she's only known as that, or some form of misdirection. Given that Maledictus has greater meaning in the Wizarding World, the latter seems more likely.

A Maledictus witch, such as the one Kim is playing, is a witch whose blood was cursed, meaning she will eventually turn into a beast of some kind; like an Animagus except without the free will. That hints at some form of transformation, and a snake seems the most likely outcome: Kim's character works in a circus, and the first trailer for The Crimes of Grindelwald has a “snake girl” on their billing; not only that, but Kim was also wearing snakeskin leggings in first look images for the movie.

It's not difficult to suggest that Kim's Maledictus is a snake girl, and there's one history-lite snake that Rowling has yet to deal with. While it's still firmly in the realm of speculation, evidence it starting towards Kim playing Nagini (especially given the additional presence of Potter-linked characters Flamel and Leta Lestrange.