Bookbinding permits it's practioners to study racial laguages other than their own. What languages would you recommend?

It depends on where you are, and what you want to know. Everiine has learned, in this order, Dracnari (to speak comfortably with his mate), Elfen (since he lives in an Elfen forest), Furrikini (I'm not sure why I did that...), and Tae'Dae, to speak comfortably with his mother.

Id say merian and elfen.

Elfen cause half the Basin is based on races that speak it.
Merian, Celests mainly Merian.

If youre either, not so certain what else.

My furry thing obsessed alt knows Furrikini, Tae'dae, Loboshigaru, and Igasho.

Let's see I've got Loboshigaru, Dracnari, and Lucidian. Lobo 'cause I used to be lobo, and the other two for the time when Gaudiguch and Hallifax are freed.

You probably want to learn Merian and Elfen, for listening in on the conversations of people from other orgs. Apart from those, you should pick ones that fit your character.

Oh, and if you're learning org languages, dracnari will be one eventually, as will either lucidian or trill, and either furrikin or tae'dae, when the other orgs are released.

Igasho, Krokani, Orclach, Taurian, and Mugwumpi. Duh!

Trill arent special enough. No language.