I've been told, by way of explaining two great-grandmothers (?) named
Christiana, that in the 19th century in England, The Pilgrim's Progress (17th century, by
John Bunyan) was frequently given as a Sunday-School prize. The hero of the first part is a man named
Christian, who journeys through various allegorical landscapes and meets people who are either good or bad influences on him. He eventually makes it into
Heaven. Meanwhile, he left his wife and four sons behind, and they eventually follow, in Part 2: the boys marry women with names like
Grace and
Mercy, and their mother's name is
Christiana. I suppose some real-life boys must have been named
Christian - it wouldn't be too surprising today - but
Christiana, with that pretty -a ending making it sound like Christie-Anna, seems to have been really popular, at least for a while.
No clue if
Krystiana is a sign that TPP was ever translated into Polish!