Katia and
Lucia go beautifully together. However,
Alexandra and especially
Elisabeth are so common as middle names that they seem meaningless. I adore
Elisabeth, but would only use it as a fn, because even if I did put it in the mn spot for a reason, many people would see it as a filler name and think that I only put it there because I couldn't think of anything else.
That said, the middle names do go well with each other and sound pleasant with the first names. I like them a lot, but if it were me, I'd keep trying. :)
I'd suggest some middle names [here are so many ideas popping into my head right now :( ] but I really have to get off the computer now, so I'll have to come back and edit some in. *Sigh*