I know they kind of had to do this for the world of the game to function but I’ve always wondered why the kids of the Vertumna group can speak to any of the Heliopause kids or soldiers and vice versa.
The Vertumna group speaks Esperanto (a manufactured language) that was created as a ‘universal’ language in our real world. It is a language that is very easy to learn and takes parts of it’s structure from many other languages. It was created in an attempt to unite people across the world and be an “international language”, so of course conservatives and fascists didn’t like it. France, Francoist Spain, the Soviet Union, Imperial Japan, and Nazi Germany all rejected, repressed, or banned the language; some even killed speakers.
Since then the language is still learnable and it is the most widely spoken constructed language in the world with 2 million speakers, but it never really took off as a universal language, instead being spoken by smaller groups across the globe.
It makes sense that the lefty hippie Vertumna Group would speak it, but it does not make sense that the fascist Earth cops would. Perhaps some of the older colonists would still have a range of their initial languages and would be able to communicate, but how would the kids who grew up speaking only Esperanto be able to? Esperanto is famously easy to learn, so since the Heliopause crash landed and now plan to stay on Vertumna, it makes sense that they would be able to learn it, but would people like Lum even try?
It’s never shown that anyone is trying to learn or that there are any difficulties in that or language barriers when communicating cross-ship. Maybe they’re all heavily relying on translators in their holopalms and it’s just never stated.