@Renu_ consider this example

ALTER TABLE some.table SET OWNER TO IDENTIFIER('`' || :owner_name || '`')

You can't use IDENTIFIER here, it throws an error (it is not a supported use case). If you try to do 

ALTER TABLE some.table SET OWNER TO `{{owner_name}}`

this gets formatted to 

 ALTER TABLE some.table SET OWNER TO `'my_owners_name'` 

Which errors because those quotes it adds are invalid here. There is NO way to format this sql with a task parameter.