Joining an element collection on a correlated inverse assocation within a subquery will cause invalid SQL to be generated.
Consider the simple model
When querying like SELECT ... FROM Person p WHERE EXISTS (SELECT ... FROM p.articles a JOIN a.coll) it will generate SQL like select ... from person person0_ where exists (select articles1_.id from left outer join article_localized localized2_ on articles1_.id=localized2_.article_id where person0_.id=articles1_.author_id).
Seems like the relation for the inverse association isn't rendered properly in this case.
Actually, it seems like the problem is in the handling of the WHERE clause within a subquery that uses a correlation when using the INDEX function in the WHERE clause. Tests with maps and the KEY function work. Don't know why it's just a problem for INDEX