Often, Agnes Moncy Guillon will use footnotes. For example on p 287 she leaves the word señoritingo untranslated and italics and adds in a footnote "the suffix -ingo makes the word extremely contemptuous". I like this kind of footnote and I wish they were used more often.
But then I found this:
[Don Pedro was] a native of the northern Province of León ...He received shipments of the famous mantecadas, cookies from Astorga, a city in northern Spain. (p 288)and, unsurprisingly, the geography lesson isn't in the original. One option for the translator would be to leave out the references: any reader who cares can look up León or Astorga to find out where they are. But it would mean that the north-Spain connections of Don Pedro might go missing for the reader. A small loss, but avoidable. So, why not footnotes again?
In a modern, Kindle-type, edition of course, the placenames could be hotlinked to their Wikipedia entries. I wonder, though, if that would be a good thing. I'm surprisingly undecided on the issue. Do we want all texts to be infinitely linked to everything else in that way?