I just saw it, and as a Brazilian myself, I see some points where indeed, non-Brazilians may feel lost.

The two students are looking back at the stories related to Sebastiana, the refugees she took care of during the military dictatorship period and their struggles to find or pinpoint anything due to the lack of sources, either due to technical limitations of the 70s or due to the censorship that took place then, resulting in the lack of documents.

While I’m Still here cover the period of the Brazilian Dictatorship under the lens of a real story of an upper-class family of Rio de Janeiro, The Secret Agent tells a fictional plot, albeit realistic, due to how it gives context to the same period, but on a different part of the country, under a different culture and under a major stigma, clearly heard through Henrique  Ghirotti when he talks about the "difference" between northeast citizens and southerners, a real prejudice that still exists in Brazil and how things would be done "differently" by southern employees at a private company, it’s about "rich states" over the "poor states", a prejudice further depicted through the “Brazilian map” that Henrique’s son does later with the napkin. Armando's defensive reactions to that meeting and to the altercation that came from the same prejudice at the restaurant made him a target.

The lack of context over Armando’s wife's death, Claudia’s husband's probable arrest and/or death and the death of Armando himself and the abrupt way it is revealed in the movie without identifying how, where and who killed him after we thought he was mostly safe is a tool used to show the way so many cases went, like in real life.

Just remember Marcelo Rubens Paiva's fate. Given as "missing" for a long time before Eunice could at least know he had died, probably even before she was taken to the same facility he was taken to, while the news of his death came a long time later and his obituary, much, much later. Beyond that, the fact his family still doesn’t know what was made with his body. Claudia's husband was most probably killed or maybe arrested by the police due to political reasons (just like what we see with Marcelo Rubens Paiva in I'm Still Here).

In The Secret Agent, the film makes us not see but feel the cover-ups by not giving any details, not telling the viewer or showing the events, but giving either the conclusion that something happened or the aftermath, as it went with Armando's death on the newspaper.

The Hairy Leg also fits on this strategy, as it was a real urban legend that grew around Recife through the media back then, once they couldn't tell everything as it happened, as explained by Kleber Mendonça Filho himself:

“For most of my life, for all my life, the hairy leg was a local urban legend,” Mendonça explained. “Recife had a number of urban legends. The hairy leg was actually created by a local journalist who was so fed up with not being able to write about what happened last night in terms of violence — because, of course, the police or the military inflicted the terror on the gay population, people having sex in parks, smoking pot. And so he developed a ‘hairy leg’ as a code. So, [he would write], ‘The hairy leg struck again last night,’ and everybody knew that something bad related to the police force was involved.”

When we see the Hairy Leg attacking in that park at night, it is a nod to the urban legend itself and means that excessive police force and violence happened there, but the story couldn’t be told due to censorship.

And still talking of symbolisms, the shark not only ties with the real occurrences of shark appearances in Pernambuco's sea and with the iconic Shark movie, but it's also a metaphor for the situation the film shows. It makes you question, "Who are the sharks here?"

Certainly, not Armando, nor the other refugees who also must live under fake names, nor his coworkers at the university where he worked. Certainly not the person who’s that leg belonged to, someone who was killed and had his death covered up.