Well, your friend, not the student, is the one using the pronunciation that fits the normal spelling conventions of English. :)
This is always somewhat subjective, and of course there is little one can do with spellings that have two or more different common pronunciations. In the USA,
Ciara can be pronounced as "see-ARE-uh", or can be an alternative pronunciation of
Sierra, or can be the original Irish Gaelic spelling of
Keira and pronounced that way. So there is no way to combine the girls named
Ciara with anything else, even though you know most of them are being pronounced identically with other common spellings.