gistfile1.txt

    multi sub trait_mod:<is>(Routine \r, :$renamed) { 
        role RenamedMulti[$name] {
            method name { $name } 
        }

        use nqp;

        my Mu $do := nqp::getattr(nqp::decont(r), ForeignCode, '$!do');
        nqp::setcodename($do, nqp::decont_s($renamed));
        r does RenamedMulti[$renamed]
    }

    proto sub foo(|) is renamed<foo-proto> { * }
    multi sub foo(Int $) is renamed<inter> { say &?ROUTINE.name }
    multi sub foo(Str $) is renamed<stringer> { say &?ROUTINE.name }
    multi sub foo(Failure) is renamed<failer> { fail('oi‽') }

    foo(42);
    foo('answer');
    foo(Failure);

OUTPUT:

inter
stringer
oi‽
  in sub foo at tmp/2021-03-08.raku line 2416
  in block <unit> at tmp/2021-03-08.raku line 2420