Oh, you're going to have so much fun :)

the phenomenon of the internet fandom (which is *totally* unknown in German academia, or at least I've never even seen a hint of it mentioned)

It can't be totally unknown, at least not among historians, because every international conference on medieval history I've attended so far had sections about Tolkien, HP, or both, and the existence of the internet fandom has been a topic on such occasions several times. I think that especially in the German-speaking countries, many scholars who know about it just don't want to admit it to their colleagues ;)