A year ago I found one of these books I wanted to download. At my son's house in Washington, D.C. it would have taken 8 hours. At my house in Omaha, fairly decent Internet connection, it would have taken 4 hours. At the university, it took 2 hours. And then what I was looking for wasn't in the book.
I haven't tested it yet on my new Mac, but considering how fast the actapublica pictures load on it compared to my PC laptop, it would probably beat that 2 hour mark. In some ways, I wish actapublica would have a download option, though, because for some of those books, there's an entry on every page that I need. Even though the book I downloaded didn't have any of my data, it was nice to be able to just page back and forth in the book.
Your process post is very well written. Perhaps you should make it a separate post with a title that might come up if someone searches the board. Although since you have Vysočina in your subject, maybe that's enough.
Side note: some of my records are from the Zleby area. I ended up finding them in the Praha archives in actapublica. Zleby is not far from Chotebor, so it is worth it to investigate multiple archives.