Publishing about Transylvania is Like Making Connections

It shouldn't matter where you publish your work so long as it is well written and edited. Really, what should be the most important thing is that you have written a book, edited a book, edited this again, have a person look it over and then get it published, with affordability in mind (if self-publishing) and professionally as possible (no matter which route you take.)
I don't think, if you write something that is full of cliches, of poor editing or of old "worn out" plots, it will matter where you publish either. Your writing is your business, and this business is hard.  Again the same holds true on whatever topic you publish on in this case publishing about Transylvania.  In other words you have to make connections to a place.

A good book is a good book is a good book, as the saying goes. The same can be said about a bad book...

I don't think it matters were you publish, if you have a good book, you are more likely to have a traditional publisher publish your work, but then again, if you know the size of your market, you will have more of a chance to know where, and how you should publish.  You have to make connections, and with history, you have to find these connections, to the place, such as Transylvania, or to people.  It is about connecting with your readers, they are smart and they know what they like.  They will make you book matter... but it's you who makes them find it good or have them enjoy it so much that it matters to them.
Again the most important thing about writing.... is writing a good book.