I've noticed that out of all the Greybeards currently living in Tamriel, only Arnegir and Paarthurnax are able to/choose to speak English. The others (Borri, Einarth, and Wulfgar) only speak in the dragon tongue. Is there a specific reasoning for this? I'm unable to find an answer on the wiki.
From the wiki
If the Dragonborn attempts to engage in conversation with any of the Greybeards in High Hrothgar besides Arngeir, they simply respond with a respectful greeting—"Dovahkiin" and a gentle bow. When they speak, the building tremors and if outside, a loud, distant bell can be heard. Arngeir can be asked to elaborate on the reason why none of the Greybeards can be engaged in conversation. The reason is that the other Greybeards' voices are so powerful that even a whisper could kill a man.