Given the introduction of new languages and means to learn them, particularly how the Underdark is presently able to have Tinker's teach any language for the mere sum of a hundred gold Once Per Reset, my suggestion is an update to the Language Ship within Cordor.
Given that the ship has a reliable rotation of some language tutors, with the addition of Primordial languages and Birb Speak, if it would be possible at all to make such available for the Surface characters to learn too.
Even if not intrinsic to the Cordor Language Ship, there are several locations in which a tutor for the languages could be fitting, with even the Astrolabe being a location in which could host such, potentially.
