The issue regarding the v12 premium should be resolved!
Edit: We've found the problem with the missing Translator's Notes for Outbreak Company 12. However, we won't be able to fix it for a few days until we can replace the current epub that we have available with a new one. We will notify you when we have a new version of the file that contains the notes available. Sorry for the inconvenience!
Edit: The version of the premium epub that is available from J-Novel Club now includes the Translator's Notes. If you are missing them in your current version of the ebook, you will have to redownload the file.