For 5.0 the plan is actually exactly that; to change how Types are "built".

I think this is again a situation where you need to step back and look at the whole. OK, the changes to HHH-7645 leads to these errors for the hibernate-envers test suite, but the larger story there is that prior to the changes in HHH-7645 the generated audit entities used the incorrect enum type as well. Given the current code the solution has to be that hibernate-envers handle this somehow. This has always been the problem with relying on the DOM representation of the mappings as the "integration" in my humble opinion. As far as I can see the only option is to change that BasicMetadataGenerator#addBasic code to set specific type parameters based on the originating Type and its configuration. Here, for example, if EnumType#isOrdinal() returns false BasicMetadataGenerator#addBasic would set the useNamed config param. Ideally envers would just reuse the EnumType instance from the main domain model; however, thats not possible given its current DOM-generation approach.

I could add null handling for that xProperty reference in the code you mentioned, but the end result currently would be envers using incorrect types in that HHH-7645 situation (and other situations with orm.xml overrides or definitions).