loving the idea of acronyms and abbreviations being fed into the language evolution and coming out the other side with new connotations!
i think SOS is an excellent example of that because it's something that would've been in common use / knowledge among people learning to communicate past a language barrier. and it's giving very militaristic, morse-code, signal-transmitter-speak vibes which i can see the COI using for cross-station communication. SOS moving from a request to an obligation is a very plausible trail of thought!
i also kinda like the idea of it being a concept that transcends the language barrier between Eden and the COI, in that it's one of those rare shared words between them that's maybe just pronounced or written differently. from Eden's perspective, "soss" is something reserved for sacred or familial obligation, because you should place your loyalty nowhere else; for the COI, it's more of a moral obligation, about doing the right thing no matter who's on the receiving end of your help, because they're so big on justice and community and rehabilitating convicts who killed ¼ of the remaining population lol. they're more righteous about it whereas Eden is more sacrificial.
and for Grace, i think definitely Simon would consider it strange that he's given so much stuff so freely out of sheer goodwill, because Grace has no "soss" towards him as a stranger (nor as a fellow brother of Eden), and the COI's definition of it doesn't typically include comfort and amenities such as valuable resources given without a fair trade in return (labour, information, etc) in Simon's experience with them. it may be "soss" for Grace to save his life rather than let him die for no reason, but that's the extent of what he owes him. Simon might feel like he hasn't "earned" that "soss" yet in terms of being given food and water, because the concept of basic human decency has changed a lot in the universe he comes from. if Grace knew the definition of the word, he would definitely argue that meeting Simon's basic needs is "soss" to him, because why wouldn't he???
thank you as ever for the ask! sorry i took a while to get to it