The movie is subtitled when Elisa has no translator and we need to know what she's saying...

At the point, we see her sign 'trivial' and Zelda translates for Strickland [and the audience]

[![enter image description here][1]][1]

After they are dismissed, she quickly signs something for which there is neither inworld nor subtitle translation - after he asks her to "Say that again" she signs it slowly and the subs give us one letter at a time..

F ... U ... \*... \*...  ..Y..O..U..

[![enter image description here][2]][2]

After Strickland asks a second time and Zelda translates as "Thank you" then we are back to accurate translation.

[![enter image description here][3]][3]


  [1]: https://i.sstatic.net/LvFhV.jpg
  [2]: https://i.sstatic.net/bGIFw.jpg
  [3]: https://i.sstatic.net/Gt8WU.jpg