This Bertanese language in dnd 5e was spoken by the Bertanese people of the kingdom of bertan of an island kingdoms of kara-tur. Basically, the proper name to this 5e language is almost unknown by the result of this no details are known about it. It may actually be a similar language like the Bavanese and/or Bawani.
Attributes Of Bertanese DnD 5E Language
Language Family: Kara-Turan languages
Spoken in: Bertan
Spoken by: Bertanese
Based on: Indonesian or Filipino