Using hurd 1:0.8.git20160522-4 from Debian:

$ ls -ld hop
ls: cannot access 'hop': No such file or directory
$ touch hop
$ settrans hop /hurd/fifo --multiple-readers
$ showtrans hop
/hurd/fifo

The output from showtrans should have been "/hurd/fifo --multiple-readers".
This happens on ext2fs and tmpfs.

ext2fs uses libdiskfs/file-set-trans.c, which recognizes "/hurd/fifo" and converts it to S_IFIFO, but ignores the arguments.  In contrast, if it converts "/hurd/symlink" to S_IFLNK, it saves the first argument of the translator as the target of the symlink (and ignores any remaining arguments).  I think it should check that it understood everything that was in the arguments, and if not, save the arguments unchanged as if it hadn't recognized the translator.