Asura and Krytan Language
" …little is known about the race before their surfacing outside of their regular contact with other underground races such as the dwarves, dredge, and skritt – the last of which they view as a threat. " https://wiki.guildwars2.com/wiki/Asura
Your guess seems to be correct
The asura and norn likely learned the language from their dwarven allies, who very much knew the common language. Though the asura surfaced only 250 years ago, they had long standing relations with the dwarves for much longer, and there were even human stories which talked about the existence of asura – but they were largely fairy tales and such. There’s even the ancient surface city of Rata Pten that predates the Cataclysm, furthering the probability of asura having had communication with dwarves and humans – likely Orrians given location – in the past.
The spoken language is not Krytan, that refers to the written alphabet, which was made standard for all cooperating races by the Durmand Priory – though some still use their own language, mainly asura, Flame Legion, and Separatists. Naturally, non-cooperating races such as the dredge, krait, and centaurs utilize their own communicative methods as well, though they’ve learned the common spoken language as well (dredge and centaurs knew such centuries ago, krait likely learned it from their prisoners they’ve taken over the centuries).
The bigger question is how the quaggans learned the common tongue, since they only surfaced 50 years ago and were otherwise in the watery depths. Every other race has had some means of communication for centuries, indicating at least a minor knowledge of the language. Except for quaggan.
Stop treating GW2 as a single story. Each Season and expansion should be their own story.
(edited by Konig Des Todes.2086)
Obviously that means we’re all speaking Quaggan.