Modern CLT
The Spraecha is what is spoken now, in 917, and needs no qualifier; this wiki calls it Modern CLT where the stages need telling apart. See Lexicon:Modern for its words and Common Reason Tongue for how it works.
Nine centuries of daily use have worn the long vowels of the Pactspraecha into diphthongs, dropped the endings, and shortened everything that gets said often. It keeps picking things up from the arrivals, because the arrivals never stop coming, and each one learns from living speakers and leaves something behind in them — which is why its sound changes never finished and why a word that resisted one is usually a word learned from somebody new.
It is one language with six accents and a good deal of local slang. Nobody in the Known World has ever needed to learn another.