i am a big fan of failing early. if you have a mess in your configuration but are only told when somebody the first time tries to create a content using this mapping, it sucks. but if that is a big hindrance to do, then lets keep it this way. if we could check with the dm if the document is translatable, it would allow a better message than the "maybe..." but not sure if you have the phpcr-odm metadata available here.