Actually There Language is very short on words. And most of it is have its core in raising children or mating. There language have not change in a long wile. The good thing is because they have so little contact they do not develop any unique dialects. Also philosophy is a favorite past time so they need words to describe the world for them self so they understand it better. Just so they can structure there minds. But that is often a more private language and is often not written down. But When a new guardian takes controle over a area after the old one is gone he often learns the old guardians private Language if he have left any written remains. There are a little odd that way that they rather get to know the dead rather then living.
And thanks for the question! I love questions!
mmh..i dont want to diskuss the hole thing....but:
1. a language must be trained the hole time...thats the problem with lost persons like robinson crusoe or recluses
2. to raise children or to mate with each other doesnt need a language...almost all animals do it witout...
and why do we teach our children the language?....that they can talk with each other later...but if there isnt someone they can talk to, its no need for a language
3. scientists are at one with each other, that sociability or living in groups/tribes/... is the starting point for language and thus for a civilisation and for sentience
another point:
im curious about what they use under water to scribe on or weapons...building materials...and stuff like that...thus the most things needed for a civilisation
because i thought alot about it, but i never found really good things...they can use, because organic things will rot too fast under water and steel requires fire...which is hard to spark under water