Valerian is a dab hand at languages and his two wards, Lilya and Constantine, speak a language called Koine. You can find the reference to Koine on page 215. Koine was the language of the Phanariots. Koine rose in the 4 and 5th centuries around Macedonia and became a regional 'super dialect' for business and trade. Koine also influenced 'New Greek.' I didn't post a link today because most of my information about Koine was contained within articles that dealt with other issues as well. However, for a quick review of Koine, there's a decent write up on wikipedia (which is not one of my preferred sources of info in general).