It is always important to consult with the deaf people in attendance and solicit their input and preferences.
Interpreters have several options on how to handle passages in Hebrew.
There are often regional preferences regarding what deaf people may be used to and prefer. Often times the rabbi will repeat the same passage in English so the deaf audience still gets the message in at least one language. Another interpreting option is to mouth the Hebrew words as best as possible. If the deaf person is familiar with the expression or prayer, this may be meaningful to them. In this case the interpreter may sign from the English.