Thanks to the earlier posters for finding out the fonts. I was able to find everything else than the Columbus MT as a free download. As I started looking for substitutes, I noticed that the fonts history is based in late-fifteenth-century or early-sixteenth-century Spanish printing creating a typeface suited to contemporary tastes and needs (http://www.fonts.com/font/monotype-imaging/columbus).
You'll find from http://typophile.com/node/88654 many suggestions what might be a good replacement. From those, the fell types (http://iginomarini.com/fell/the-revival-fonts/), seem to be the only free choises. And from those, I'd imagine you would like to choose one that is not too quirky to maintain good readability. So, whith that in mind, I'm going to try French Canon, Double Pica and Great Primer.