The question states that the phrase about the ants cannot be about literal ants but can only be an allusion to the expression "avoir des fourmis". However, due to naïve first-person point of view from which the entire story is told, it is plausible that the literal meaning is also at work. The word choice makes this plausible in two ways: first, there is the verb "vient" (from "venir", to come) whereas the expected verb is "avoir" (to have); second, no body parts are mentioned. Below is the relevant part of the entry "fourmi" in the dictionary Le nouveau petit Robert (2006):
Avoir des fourmis dans les membres, dans les jambes, y éprouver une sensation de picotement (comparable à la sensation que procuraient des fourmis courant sur la peau).
(Literally translated: Have ants in one's limbs, in one's legs, feeling a sensation of prickling (comparable to the sensation of ants crawling on one's skin).)
Another verb that may be used here is "monter", as in the following example (Après les confinements, ils n’osent plus sortir : c’est quoi le syndrome de la cabane ?, Sud Ouest, 25/05/2021):
Les jours suivants, lorsque je me préparais pour sortir, je sentais monter des fourmis le long de mes bras, de mes jambes.
The literal meaning is also made plausible by the context: the narrator has been standing completely still for a while because he is standing on a landmine. (He heard a click sound when he walked onto it and has told the other in his company to march on and leave him behind.)
But that same context simultaneously makes the figurative meaning plausible: he is feeling pins and needles because he has been standing still for so long. Based on this, both meanings are present in the title and in the story's last sentence. Since "ants" don't have the same figurative connotation in English as in French, the translator is faced with a dilemma. Should they preserve the literal meaning and lose the allusion? Should they just keep the metaphor and lose the irony of a man surviving war battles but being floored by ants? Or should they try to find an alternative formulation that both refers to insects and "pins and needles"? In situations like this, each translator must make up their own mind. Some solutions are better than others; it is usually not a matter of "correct" versus "incorrect".
A similar problem can be seen in the translation of the film title Dead Poets Society. It was translated into German as "Der Club der toten Dichter" (literally, the club of dead poets), narrowing the title down to just one meaning and losing the other meaning, namely "society in which poets are dead" (i.e. in which poetry has disappeared). The film title was translated into French as Le Cercle des poètes disparus (similar to the German translation) or as La Société des poètes disparus, relying on the double meaning of "société" as "society" and "association". Strangely, according to Wikipedia, the latter translation was only used in Quebec and not in France. The film's Canadian distributors apparently understood the title's double meaning better than their counterparts in France.
