Starfish Language: Oh, plenty of them. Esseli native language, for example, is encoded on RNA strands (although fortunately they can and are more than willing to add extra speech organs as required). Mirilasté language is also notable for using sequences of musical notes as its “phonemes”, and volume and tempo are as linguistically significant as pitch. Seb!nt!at and various other solar clades, along with the galari‘s techlepathy, tend to use dialects designed to be transmitted electromagnetically and which translate very poorly into audio. The qucequql and thegas-giant dwelling sssc!haaaouú use bioluminescence and chromatophores to display changing bands and patterns of color as a form of “speech”. The mezuar communicate chemically, but primarily communicate through direct neural linkage where their roots and branches grow together. Myneni communication has both a chemical dialect and one based on a very flexible chime-and-whistle audio generation that most more conventional larynxes can’t manage. (And the uplifted dogs, of course, retain a certain facility for scent-based communication.) The nsang communicate principally by writing with spinneret material, in two-dimensional ideograms, augmented by gestures for simple or immediate concepts.
Of course, that’s just the first layer. Once we get into the difficulties of coping with higher-level grammatical quirks of the language: galari is structured like hypertext; digisapience communication is often discrete heavily-internally structured concept formats designed for packet transmission as high-speed data pulses (“here, have a wiki-database of my communication”); the múrast and embatil, as collegiate intelligences, throw out the tree-structure of most languages in exchange for matrix-hashes – and the mirilasté, curiously enough, use something more like a stack – seb!nt!at is a quantum language, in which it’s possible to tell three stories at once and then collapse the meaning at the end of the sentence; native whale, although fortunately not standard dar-ííche, doesn’t have sentences, but rather indefinitely long songs – whose individual phrases are even more long-winded than Entish – in which everyone can talk at once (their audio-processing brain finds resolving the threads of conversation trivial) and, indeed, modify each others’ sentences on the fly…
…and the difficulties of relatively simple issues like non-gender genders, attitudinals (very important, since They Do Not Speak Nonverbal), evidentials, context-dependent or referential concepts, alien metaphors, different methods of categorization or metaphysical perspectives on time, space, and reality – things get very weird very quickly.
Even Eldraeic, which was designed as a lingua franca for a polyspecific polity, suffers from this – since due to its ecumenical nature, it includes a very, very large set of optional grammatical features designed to cover as many of the quirks of the above languages as possible, a mode-switching grammar, three alphabets, an ideographic representation, and multiple isomorphic dialects to be spoken in different environments and with different apparatus, including underwater, over digital communications channels, by color, and even with nothing except pause and interval. Speaking pidgin Eldraeic (which is to say, Trade) is easy – but speaking many of the more complex forms is very much not, and its capacity for willful obscurantism is generally acknowledged to be unparalleled.