Hey Marco Perazzo,

I'm affraid it's still not enough, I adapted my test case and it still passes: https://github.com/yrodiere/hibernate-search/blob/HSEARCH-2536/orm/src/test/java/org/hibernate/search/test/engine/NumericFieldOnSuperclassIdTest.java
Did you manage to set up a failing test case?

Are those known issues also relevant when using Elasticsearch as backend, or only when using the old Lucene backend?

They are mostly relevant with the embedded Lucene backend, as far as I know.

What exactly does not work when trying to sort the document ID? Is this documented somewhere?

This is not documented, we just happen to know some things are wrong with document ID customization, but it's low priority so we haven't investigated yet.
Actually, we did not intend to provide any form of customization on the document ID, and it has been added almost by accident. Which is why we don't recommend to do it, and we even plan to remove support for such customization in Hibernate Search 6.0 ( HSEARCH-2543 Open ).

Are there any other important issues with a numeric document ID you did not mention?

None that I'm aware of, at least.