User blog comment:Gracedharperd/Witch Cult Sin Archbishops Theory/@comment-4436931-20161226005927

About Sirius:

It's also important to note that the author didn't add the Sirius short Re:Zero but rather as its separate story, so it may not exactly be canon. There wouldn't be any point in Pandora reviving Fortuna anyway

About Petelgeuse:

As the author's already mentioned, the change is intentional, he does know that the actual star is called Betelgeuse