It's possible unmarked reels are lying around somewhere in storage, but who's ever going to find them? Sadly, film and tv preservation is quite bad, even in Western countries, and people only make an effort to hunt down big name stuff. We have found a lot of old 20s movies in third world countries, but since Messenger of Allah was probably never screened outside Japan it's very unlikely.
I've always found this series interesting. It comes from a time where Islam/Middle East was this far away and exotic, not all war and terrorism. Hard imaging someone making this kind of stuff nowadays.