Every novel by Yuri Herrera teaches you how to read it in the opening scene. His debut, Kingdom Cons, begins with a musician watching a king shoot a drunk man in his court. The victim’s offence? He refused to pay the musician for his song. The novel unfurls into a parable of patronage and art, cartels and complicity. Signs Preceding the End of the World opens with a young woman named Makina witnessing a sinkhole swallow a man, a car and a dog. I’m dead, Makina thinks, and the novel plunges into a journey from Mexico to the United States to find her brother, its chapters modelled on the underworlds of Mexican mythology. The Transmigration of Bodies starts with a hungover man stumbling out of his house in search of water. He notices the silence first, then “a dense block of mosquitos tethering themselves to a puddle … as though attempting to lift it”. The puddle is blood, and the silence is death. A plague has arrived in the night.

Like his previous novellas, Season of the Swamp follows a nimble, reluctant interloper as he learns to navigate a dangerous new environment. It also calibrates our attention in the opening scene, but even before teaching us how to read it, this novel teaches us why to read it. In a preface, Herrera writes: “1853. Benito Juárez has served as a judge, deputy, and governor of the state of Oaxaca. But he has yet to become the man who will lead his country’s liberal reform, first as minister and then as president, and he is certainly not the hardheaded visionary who will lead the resistance against France’s invasion of Mexico and restore the republic.” In his autobiography, “Juárez says not a word about his nearly eighteen months in New Orleans … despite the fact that it is there he evolved into the liberal leader who would transform the trajectory of his country”. Benito Juárez, orphaned at the age of three, would one day become Mexico’s first Indigenous president, prying his country back from the vice-like grip of the aristocracy and the Catholic church. Biographers agree that his exile in New Orleans was formative, but no one knows what, exactly, happened there. Who could bring this story to life better than Herrera? A novelist of unparalleled tonal agility and negative capability, one with a passion for archival research, who has split his time between Pachuca, his home town, and New Orleans for the past 13 years.

Like his previous novellas, this one begins with its protagonist witnessing violence. Benito and his brother-in-law watch “badges” (policemen) drag an enslaved man from a ship, thwarting an escape. The badges club the man and order him to drop the compass he’s cradling to his chest. Herrera wrote much of Season of the Swamp during pre-vaccination Covid-19, and when I read these lines, I can see the white officer kneeling on the neck of George Floyd, killing him on a public, daylit street as he asked for his mother. Season of the Swamp is about the galvanising power of witnessing. It’s about a revolutionary finding his compass. It also, unfortunately, suffers from an uncharacteristic, unignorable vagueness: vagueness of syntax, character and scope.

Benito and his fellow exiles spend the book wandering Herrera’s meticulously researched reconstruction of 1853 New Orleans. They witness bear fights, poor sewage systems, operas, dead bodies, sex work, duelling pianos, horse races, public executions and numerous parades. They find and lose housing, get drunk, discuss politics. Benito finds work at a printing press, then a cigar shop. He becomes infatuated with a Black woman named Thisbee who sells the best coffee in town. Her true vocation, however, is helping enslaved people escape to freedom. Benito befriends the Cuban poet Pedro Santacilia, who takes him on a harrowing tour of a market that sells human beings. New Orleans was the epicentre of the United States slave trade, and Herrera animates Benito’s experience with factual details of slavery’s daily horrors. Mexico outlawed slavery in 1837 – 16 years before the real Benito Juárez arrived in New Orleans – and the novel suggests that it was his encounter with the American slave trade, above all, that transformed Benito into the leader he became.

Herrera’s exceptional sensitivity to language, penchant for neologisms, ear for regional dialects and dexterous shifts in register make him uniquely challenging to translate. Fortunately, Lisa Dillman has risen to every occasion, brilliantly sailing all of Herrera’s work into English. While she has described him as “astonishingly hands-off”, their dynamic is more collaborative than most; Herrera is fluent in English, and the two maintain an open channel of communication as she works. Despite his propulsive plots, I don’t read his work to find out what happens, but to find out how he (and Dillman) will describe it.

The thick linguistic fog of Season of the Swamp is therefore aberrant. The English translation keeps Benito unnamed, referring to him only as he and him, which is especially confusing in a novel with a large cast of men and very few women. In addition to the pronoun slippage, the diction of the novel can be disorienting. Season of the Swamp is cluttered with the vague syntax of a rough draft, paired with culturally and temporally dissonant phrases. I delight in thoughtful anachronism, but it was jarring to encounter an abundance of contemporary American vernacular. Often, I felt I was watching a McDonald’s bag tumble-weed on to the set of a period drama. When semantic haziness obscures characterisation, the damage is more consequential. Season of the Swamp instructs us to read Benito’s inner life as the stage of its primary drama. Unfortunately, very little is visible in this theatre. When we meet him, Benito is 47 years old and he has already made a political impact substantial enough to get him exiled. In place of an interior life, however, we find notes toward an interior life. Even his encounters with the kidnapping and sale of human beings are rendered in bizarrely flat language; from both Juárez and Herrera, I longed for more than prosaic reflections on the general badness of slavery.

As I tried to identify the fundamental software bug of this novel, I kept returning to the opening of the second chapter, a curious cascade of language: “The most pivotal thing to happen in the weeks that followed was the drumming; no, the most pivotal thing in the weeks that followed was the dances; no, the most pivotal thing in the weeks that followed was the concerts; no, in a way it was kind of the hippodrome, which was fun and also pivotal though in another way …” Further candidates for most pivotal thing to happen in the weeks that followed include the “inner courtyard”, meeting “the canaille”, learning “what funk was”, and “more or less” figuring out “what Thisbee might or might not have done”. On my first read, I read this as an unsuccessful form of linguistic play. By my fourth reading, however, its rapid descent into absurdity began to register as the author’s confrontation – conscious or not – with the formula he has chosen. He decided to write a novel about a chrysalis of time in which a regular man transforms into a Great Man. But what if he fundamentally rejects the Great Man trope of history? What if Herrera – who chose to write about a leader’s pivotal months in exile – rejects the most pivotal thing as an organising force of identity and narrative? The opening of the second chapter seems to say: look how ridiculous this formula is. From the start, it was clear to me that both Herrera and Benito are too interesting to collapse 18 months into three-act structures, tidy conclusions, lessons learned. Regrettably, Herrera never offers an effective alternative. The novel was built on sand. Or perhaps more accurately: on a swamp.

Compared with his previous work, Season of the Swamp reads like notes toward a novel rather than a final manuscript. It is distracted, muddled with placeholders, declaring its purpose every few chapters while desperately searching for one. It is my love for his work – along with Dillman’s delicate, adept translations – that forces me to notice the perfunctory nature of this novel. Herrera’s rough drafts are better than most people’s final drafts, and many descriptions within this book – of languages and crowds, music and ecosystems, tenderness and violence – sing. Perhaps it is unfair to hold a genius to his own standards, but Herrera is a sublime astrological event that will never again occur in my lifetime. I can’t hide my disappointment when he behaves like an average star.

• Season of the Swamp by Yuri Herrera, translated by Lisa Dillman, is published by And Other Stories (£14.99). To support the Guardian and the Observer buy a copy at guardianbookshop.com. Delivery charges may apply.

• The Rabbit Hutch by Tess Gunty is published by Oneworld.