Нет, нельзя. Причем это ограничение не столько GUI, сколько самой ZFS.
Code:
The pool name must begin with a letter, and can
only contain alphanumeric characters as well as underscore ("_"),
dash ("-"), and period ("."). The pool names "mirror", "raidz",
"spare" and "log" are reserved, as are names beginning with the
pattern "c[0-9]".
Но можно назвать по-русски саму шару, если очень надо.