Erik,
I reproduced your case.
In my case I see the error marker on basename attribute of <f:.oadBundle /> tag (which tells that message bundle not found) and the warning on each property usage (like #{msg.some_property}.
As workaround I can suggest you to create yet another bundle demo/msg.properties (without any location specification). In my case this removes the resource bundle related errors/warnings and makes open-ons to work for bundles and bundle properies (the bundles specified as default locale will be openned, but not this 'fake'-bundle)
Sorry for inconvenience,
Victor Rubezhny