I check this issue, and I afraid so it is not fixable. The target list entry related to session variable has not some magic value like ?column? that can be used for check if tle->resname is implicit or explicit
And in this time I cannot to use FigureColname because it doesn't work with transformed nodes. More - the Param node can be nested in SubscriptingRef or FieldSelect. It doesn't work perfectly now. See following example:
create type xt as (a int, b int);
create view b as select (10, ((random()*100)::int)::xt).b;
\d+ b
SELECT (ROW(10, (random() * 100::double precision)::integer)::xt).b AS b;
