When you append datatable to a journal, it will be converted to Table Box with different type col boxes, widths don't seem to get copied over and you cannot have multiple lines in "normal" type col boxes. You can try to use some weird workaround like this, where you edit the table box and add extra column to it (col box can have multiple lines...)
Names Default To Here(1);
dt = Open("$SAMPLE_DATA/Big Class.jmp");
jrn = Current Journal();
dt << journal;
Column(dt, "name") << Set Display Width(150);
dt << Set Cell Height(100);
rep = dt << get as report;
tb = rep[TableBox(1)];
tb[1] << Set Width(150);
tb << Append(cb_hidden = Col Box("hidden", Text Box("", << Set N Lines(2))));
cb_hidden << Visibility("Hidden");
rep << journal;
There are hopefully better methods than this.
-Jarmo