It's an extended riff / parody / pastiche / fanfic of a story called Tlön, Uqbar, Orbis Tertius by Jorge Luis Borges. And it has references to other Borgesian works like The Library of Babel and Funes the Memorious. It emulates Borges' style: precise, erudite, haughty, and full of asides referencing obscure works (only some of which are real). His stories often employ some kind of framing device, e.g. some fictional scholar commenting on a fictional work, or a government report of some incident; this is what the French bit at the start is doing (you can just put it through Google translate).

Tlön, Uqbar is only 16 pages long; you can read it in one sitting and thereby get 90% of what Gwern is doing here.

https://sites.evergreen.edu/politicalshakespeares/wp-content...

As for the part you excerpted: don't worry about understanding every little reference. Just let it all wash over you and enjoy the ride, then maybe look things up afterwards. To an extent, you're supposed to feel a little intimidated, that you're a bystander not fully in on the joke. It's like a magic trick.

(And "signal" here is used in the adjectival sense "[s]tanding above others in rank, importance, or achievement" https://en.wiktionary.org/wiki/signal#Adjective )