The message keys will always be connected to the attribute_id to keep it generic enough. Otherwise we would have attribute keys in contacts. and in acs-translations, which I don't think makes a lot of sense. So, if you populate, you have to use the lang::message::register calls along with it. Probably a PITA when you have you custom package and you want to maintain it in multiple languages, but there was this tradeoff decision and I think the way it is done at the moment is the more sustainable one.
