To my knowledge, the question of what to do about the language Rhaya was never definitively answered. All the Master Atlas says is that Rhaya 'is a language with seven very distinct dialects'.
Consider this: Sky Giants of the Brass Stair, Cloudlords of Tanara, Norek, Demons of the Burning Night, and Quellbourne all contain references to languages spoken in Jaiman.
Question: Does 'distinctly different' mean learning each dialect separately?
Take the real-world example of the Low German language family. English, Dutch, and Afrikaans all belong to this language group. However, I would be hopelessly lost in a conversation with someone from either country.
My choices for Dialects of Rhaya:
1) Quells (Quellbourne)
2) Nore (Spoken in Norek and U-Lyshak)
3) Ranaka (Spoken in Tanara)
4) Zorin (Spoken in the Zor Wastes and Northern Rhakhaan)
5) Nureti (Spoken in the Mellurian States and Southern Rhakhaan)
6) Alaros (Spoken in NE Jaiman)
7)
?