it is.
do you have a pootle account?
https://translation.torproject.org/zh_CN/gettor/
if i were doing it, i would click on "show editing functions", then "po file", download it, and edit it in my favorite text editor
because the strings are quite long, so doing it in pootle might be clumsy
on the other hand, there are only 6 strings, so maybe pootle isn't so bad