The four messages are each centered on a word. If focus is directed solely to italicized elements:
Rivers: Phonetically, we have Mississippi, Amazon, Missouri, Columbia, Tennessee, the Nile, Fraser
Widows: Natasha Romanoff, ‘Widow Maker’ heart attack, Widow’s Peak, Black Widow spiders
Orphans: Oliver Twist, Steve Jobs, the Baudelaires, Annie Bennett, Batman, and (Harry) Potter are orphans
Rags: all italicized phrases are popular ragtime pieces.
It's possible to find some disagreement over the meanings of some of these terms, but sources
that refer to the Chicago Manual of Style (which sadly is itself not generally accessible) agree.
Rivers: Noticeable lines consisting of spaces that run through 3+ lines of paragraphs.
Widows: Paragraph-ending lines that fall at the beginning of the following column/page.
Orphans: Paragraph-starting lines that fall at the end of a page.
Rags: Jagged right edge of left-aligned text.
If you look for instances of these four typographical errors in the puzzle itself:
Seven (intentional) vertical rivers in the document ‘point’ to a word at the bottom of the river (highlighted blue), spelling “IMMEDIATELY FOLLOWING DESSERT IN MATISSE’S RED ROOM.” The full title of the artwork is “The Dessert: Harmony in Red”, so answer is HARMONY.
Isolating solely the widows (highlighted green) in the document, one gets the message “PABLO’S GLOOMY PERIOD FEATURING THE OLD GUITARIST”. The answer is BLUE due to Picasso’s Blue Period and his painting The Old Guitarist.
Isolating solely the orphans (highlighted red) in the document, one gets the message “SOMEWHERE AROUND 1907-1908 THE KISS (THE FAMOUS ONE) WAS MADE WITH THIS KIND OF LEAF”. The answer is GOLD due to Klimt’s famous The Kiss which was made with gold leaf during those years.
Reading off the words in the ragged edges (highlighted purple) in sequence, one gets “JACK THE DRIPPER FOR POLLOCK E.G.”. Jack the Dripper is the NICKNAME of the artist Jackson Pollock.
Putting these subanswers together with the template at the bottom, we get HARMONY IN BLUE AND GOLD (NICKNAME). This artwork's nickname is the answer: THE PEACOCK ROOM.
The goal of the puzzle was to make an object that looks radically different if you view it from a different angle, but for text. In this case, viewing words as things with meanings vs mere ink set on a page. Although the puzzle is quite intimidating for teams giving it a quick glance (1,000 words of data!), the hope is that solvers learn to focus on the italicized words (and, later, typographical categories), as only about 50 words were relevant to the solution.
Originally the sections had widows, orphans, rivers, and runts (when the last word of a paragraph falls on a line of its own). It still had combining the four subanswers to get a question, but the answer was RAGS (which was then itself used to extract the final answer). Many issues with this led to the streamlined final version (two being: it was really easy to short-circuit once you figure out typography, and if you've dived through enough typography blog posts to discover 'runts', then you've already seen 'rags' ... so it was underwhelming to have 100% of your work for the past hours culminate in something you already know).
As for the construction of each section, it began with the feature (e.g. 'widow'), which led to a couple emphasized words serving as the nucleus for writing out some silly content (this was the most fun part). With a loose 'story' planned out, it then became a creative puzzle itself to try to embed clues via typographical features through only slight modifications to the content and to the spacing (~350 of the spaces were manually set via LaTeX to a specific width).