Replace with the following. (Note the use of @@92 as a string escape, to include a literal backslash character, and @@124 for a vertical line.)

Constant U_POS 28; Constant W_POS 30; Constant C_POS 31;
Constant E_POS 32; Constant IN_POS 34;
[ DrawStatusLine i;
    @split_window 3; @set_window 1; style reverse; font off;
    @set_cursor 1 1; spaces (0->33)-1;
    @set_cursor 2 1; spaces (0->33)-1;
    @set_cursor 3 1; spaces (0->33)-1;
    @set_cursor 1 2;  print (name) location;
    @set_cursor 1 51; print "Score: ", sline1;
    @set_cursor 1 64; print "Moves: ", sline2;
    if (location ~= thedark)
    {   ! First line
        if (location.u_to ~= 0)  { @set_cursor 1 U_POS; print "U"; }
        if (location.nw_to ~= 0) { @set_cursor 1 W_POS; print "@@92"; }
        if (location.n_to ~= 0)  { @set_cursor 1 C_POS; print "@@124"; }
        if (location.ne_to ~= 0) { @set_cursor 1 E_POS; print "/"; }
        if (location.in_to ~= 0) { @set_cursor 1 IN_POS; print "I"; }
        ! Second line
        if (location.w_to ~= 0)  { @set_cursor 2 W_POS; print "-"; }
                                   @set_cursor 2 C_POS; print "o";
        if (location.e_to ~= 0)  { @set_cursor 2 E_POS; print "-"; }
        ! Third line
        if (location.d_to ~= 0)  { @set_cursor 3 U_POS; print "D"; }
        if (location.sw_to ~= 0) { @set_cursor 3 W_POS; print "/"; }
        if (location.s_to ~= 0)  { @set_cursor 3 C_POS; print "@@124"; }
        if (location.se_to ~= 0) { @set_cursor 3 E_POS; print "@@92"; }
        if (location.out_to ~= 0){ @set_cursor 3 IN_POS; print "O"; }
    }
    @set_cursor 1 1; style roman; @set_window 0; font on;
];