Language in the most primal sense of the word, is a convention for communication between separate entities.
Humans have the most developed languages. We have dialects and jargons too many to count, but these aren't the only languages out there.
Complete with grammar, syntax, morphology, orthography, and a lot more, programming languages can be considered convention for communication between humans and machines. We can tell our computer what to do, and it gives us feedback.
Mathematics can be a language, too, considering its also just a convention of axioms and propositions.
Maybe dolphins have their own grammar of echolocative squeaks. Ant colonies can have their own pheromone codewords. Satellites might be talking via radio frequency modulation.
When we get right down to it, all languages are simply just social cues, regardless of what sensory medium is available for the task.
Organized Synesthesia is the biological version of multimedia arts. Within the brain, synesthesia occurs as an interpretation of sensory data from a sense organ that is somehow associated with a type of sensory data from a different sense organ. The idea of hearing smells and tasting emotions probably leads to disorganized thoughts, but enhances the synesthete's pattern recognition abilities.
But by making the recognizable patterns available for correlation to consequently develop entirely new "meta-senses" arising from those correlations, maybe we can re-organize thoughts even better. The simplest example I could give would be a sensory ability made for sentient photosynthetic organisms, designed to find the optimal light settings to have enjoyable meals with maximum nutritional value. Simply put, a creature can taste the rainbow and the sunlight by having:
a heightened sense of sight for accurately gauging the polarization of light rays, the interference fringe patterns they create, and the ranges of frequencies they generate
a dynamic sense of taste for correlating what properties of light gives the most pleasurably nutritious tastes
Organized synesthesia could be achieved by conscious correlations of sensory data, enhancing both pattern recognition and interpretation
Noumenon is the opposite of phenomenon. It is a thing as itself, an object's fundamental existence as opposed to a thing as represented by other things.
If somehow, other sensory perceptions, correlations, and interpretations, are heightened and integrated altogether as to build a comprehensive copy of reality within the mind, wouldn't that create noumena out of raw phenomena?
Likewise, a multimedia communication system that involves recreating the noumena by exhibiting all their constituent phenomena should be possible as well.
A thing-as-itself can be made communicable by integrating and exhibiting the thing-as-it-appears from different sensory perspectives
Everybody knows telepathy is simply a remote transmission and reception of thoughts. Adding empathy to the mix however, allows the broadcast of emotions, feelings, sensations, experiences, among similar abstract concepts, that all seem to be very differently interpreted by each individual as based from their own experiences and memories.
The four topics I discussed are more tightly related than I may have discussed them, but the simple premise is that language, thought, and perception will merge into a single concept.
If the answer is yes and a convention for mixed sensations will indeed provide people with the privilege to broadcast the entirety of themselves, what would become of such a society?
But if no, and allowing ourselves to consciously develop mixed sensations and be able to communicate them more efficiently still cannot allow us to completely and truly understand one another, then what can?