Agents do not have a language that they speak to each other, exactly, they don’t need one, since the magic in their bodies harmonizes when they are near each other, essentially allowing them to read each other’s minds and experience each other’s emotions.
But Agents aren’t entirely language-less despite this. They free-associate in their own minds, creating symbols, labels and relationships between ideas and arranging them in patterns of their own devising. They do use these symbolic plays of concepts and imagery when they “talk” to each other, but there’s no agreed upon system, they understand because in close contact they can take in the expression as well as experience expressing it at the same time.
Agents often try to use the words in languages they learn according to their personal symbolism and associations with concepts, sounds and memories - or they may slip into doing so without realizing. The effect can range from poetic to total word salad.