Function-based index usage mismatch in user-defined routines

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WITH indexes AS (SELECT schemaname, tablename, indexname, indexdef, 'lower' AS opposite_function
FROM pg_catalog.pg_indexes
WHERE indexdef LIKE 'CREATE UNIQUE INDEX%' AND 
indexdef LIKE '%(upper(%'
AND
schemaname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL)
UNION SELECT schemaname, tablename, indexname, indexdef, 'upper' AS opposite_function
FROM pg_catalog.pg_indexes
WHERE indexdef LIKE 'CREATE UNIQUE INDEX%' AND 
indexdef LIKE '%(lower(%'
AND
schemaname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL)
),
indexes_with_opposite AS (SELECT schemaname, tablename, indexname, indexdef, opposite_function, translate(substring(indexdef,'[(][^()]*[)]'),'()','') AS indexed_column
FROM indexes),
routines AS (SELECT 
  pg_namespace.nspname AS routine_schema, 
  pg_proc.proname AS routine_name,
pg_get_function_identity_arguments(pg_proc.oid) AS parameters,
  array_to_string(proconfig, ',') AS search_path,
  pg_get_functiondef(pg_proc.oid)  AS routine_src
FROM 
  pg_catalog.pg_proc, 
  pg_catalog.pg_namespace
WHERE 
  pg_proc.pronamespace = pg_namespace.oid
 AND prosecdef=TRUE
AND pg_namespace.nspname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL))
SELECT schemaname AS table_schema, tablename AS table_name, indexdef, routine_schema,  routine_name, parameters, regexp_replace(routine_src,'[\r\n]','<br>','g')  AS routine_src
FROM indexes_with_opposite AS io, routines AS r
WHERE r.search_path ILIKE '%' || io.schemaname || '%' 
AND r.routine_src~* (opposite_function || '[[:space:]]*\([^\)]*' || indexed_column)
ORDER BY table_schema, table_name;