Sign language of Deaf when it's their first language is strange enough, it does have something map-like that the author writes about. Curious that practically nobody is nerding out on it, unlike various aliens mentioned. My personal observation is the Deaf culture is so extrovert that it's actually repulsive to nerds. That the language does not have written form is not helping.

Imagine that, hyper extrovert aliens that are understudied because they feel acutely icky to all introvert humans lmao.