I mean this is all a hypothetical, so let me throw some blockers at you:

They don't distinguish between wave and not-wave, assuming they dont have a Lacanian concept of language and their pre-language concept of what we would call a wave is actually the average distance from the bottom of the ocean in an arbitrary field of qualia whereby they average out "extended" phenomena from an "unextended" experience of the average of the different forms of background radiation.

In which case they couldn't count a planet rotation and have no concept of counting or rotation but would express it instead as an average speed and direction in relation to the absorbed radiation of different astral and planetary (by which I mean "terrestrial" for lack of a better word when not talking about our planet) bodies? So what is a year to us is a limitless expression of the average rate of change of the comparative rate of radiation from the nearest star and the largest vent in the bottom of their ocean? They express this by making parts of their carapace emit different strengths of radiation in different directions. Would we even know to call those emissions a language?

edit: to make it even harder, maybe there's a way to experience a qualia of alpha radiation to them that for them is as different as the words "because" and "apple", but to us is two identical blasts of alpha radiation because we don't even know how to sense the differences that are there because to us they don't even exist?