Philipp the issue is that the driver doesn't know the language. The same as it doesn't know anything of the other metadata we keep in sys_file_metadata. It basically only knows the values we store in sys_file.
Well, the driver creates the information in sys_file. It and only it can provide any information about the file. I do not say that the driver needs to provide this information, but - depending on the storage - it might have that information at hand (e.g. knows about variants, etc).
I don't think we need to have a automagic solution here. Just give the editor an option to set the contents_language and the related file
That is to error prone. Editors will forget it half of the time and it requires manual intervention, therefore troubling any automated process.