Of course one can also add the new JBL version to the WF 8 module ZIP if that's what one is after.

Interesting. Are you sure that would work? It's pretty hard for us to test all logging statements within (deployed) integration tests. I wouldn't be so sure that the new JBoss Logging API is able to wire itself up to the WF8 logging backends.
More importantly: is it worth the hassle? The JBL upgrade doesnt't bring us any benefit.