"Super-fluentest" is not a word recognized by standard English dictionaries, and therefore, is not a word that has any synonyms related to it. However, assuming that the intended meaning behind this word is "most fluent", some synonyms for "fluent" could include articulate, eloquent, well-spoken, expressive, and lucid. Each of these words suggests a high degree of proficiency in communication and the ability to express oneself clearly and effectively. Other alternatives could include the words glib, slick, or smooth, which suggest a certain level of effortless ease in speaking but may not carry the same level of connotation of proficiency and expertise as the other synonyms.