From chapter 13: "For father (linguists) there is also clack clack Mou."
Seems Mou also has some interest in language and is trying to help our protag learn lamia.
Speaking of Lamia, that language structure for speaking to other races is wild.
The Lamia are translating from their own language into an approximation of harpy which is used to convey old wolf which the protagonist knows from the local pidgin language, all the while listening back through the vibrations in the boards.