So I tried running the i18n demo with the *.gwt.xml you posted and didn't see any issues. Then I added in the Baz.* files you posted and I was able to observe Baz.foo not being translated. But afterwards I deleted the gwt-codeserver-*.tmp folder in /tmp folder and now I am unable to see the problem again.
I'm still not sure what the problem is exactly, but it seems like it can be fixed by deleting the codeserver's cache files after adding a new @Bundle annotation.
Cleaning up all caches solved the problem, but I had to wait for the /var/folders/tmp* directory to disappear after I ended SDM... this is frustrating.