Right, I suspect there’s nothing to see here. This is a simple use case that’s tested again and again in our test suite, so I’d be surprised if there was such a blatant bug.
On the other hand, I wouldn’t be surprised if your Hibernate Search 5 “numeric” bridge actually indexed your property both as text and as a number. That’s a very, very common thing in examples of Hibernate Search 5 bridges I saw on the web.