I always found the Circle Trigonists a bit... goofy. Their generic insignia, their unspecific ideology, the fact that they apparently managed to take control over most of Western Europe in a few years, the odd uniforms, the weird ranks...
What is hilarious for me, however, is the choice of Esperanto for their language. I get that the use of some sort of language that wouldn't offend any nation was necessary, and Esperanto, being international, was the perfect choice. However, a language whose creator and majority of speakers are avowedly cosmopolitan and pacifistic being used for a militaristic, expansionist and authoritarian nation is a bit ironic. I doubt the Esperanto community was happy with this.
I've always found the Aggressors endlessly fascinating, and this article did a good job to shed light on its military- and rank-related weirdness.
I found more information on rank insignias, special Trigonist decorations for heroism and the nation's fictional history here:
https://www.alternatewars.com/WW3/Trigons/Trigons.htm.