Linguistic And Other Changes

"Flight to Forever."

Would Saunders and Belgotai be mutually comprehensible with a gap of a thousand years between them? 

We are told how English has changed:

Belgotai has a slurring accent although it becomes easier to follow with practice;

vowels sound different;

consonants have been modified;

"r" is more like twentieth century French or Danish;

foreign words, especially Spanish, have been incorporated.

"Chronning," chronology, has also changed. Belgotai does not recognize "nineteen seventy-three." 

"...modern chronology dated from the ascension of John Mteza I." (p. 180)

- because the late twenty-seventh century Planetary League and African Dissenters had ended the earlier Armageddonist/Fanatic rule.

Some of this sounds like (a different version of) Poul Anderson's first future history series, the Psychotechnic History.

Onward.