I couldn't find full names of either character (if they even have them) from reviews, synopses or the first couple of chapters of the original web novel. So I just added their given names.

Kuuna's family name, "エルシエ" (romaji: erushie) is referred to in this episode.
http://ncode.syosetu.com/n8925cq/74/
"エルシエ" is her homeland's name, which first appeared in the prequel of the novel.
http://ncode.syosetu.com/n5705ch/22/
The etymology of "エルシエ" is described as a combination of "エル" (blessing) and "ルシエ" (the heroine's name).
But I couldn't find the origin or official alphabet spelling of these words in neither the web novel nor the published book. So I adopted the romaji spelling as the tag name.