If I interpret it as (A↔Z, B↔Y, etc.), here’s what it decodes to:
Thmyl scratched his beard. "That’s nonsense. Even for you." --- thmyl lbt draghwn bwl zd kakarwt llandrwyd Apk
"Why?" he asked.
But the apk shimmered, and its static resolved into a map: the draghwn (dragon) bwl (bowl) was a crater at the mountain’s heart, and "zd" meant zephyr's dawn . If I interpret it as (A↔Z, B↔Y, etc