What are the values of x and y in the above sequence?

I agree that the last two postings probably are the key to the intention of this problem. In English and French "x" is in position 23 (letter "W" of the alphabets) and "y" is in position 25 (letter "Y" of the alphabets). (German would be a little more tricky since it uses "Y" only in loan words, so one would have to decide whether it counts in that alphabet. -- but that could be avoided by the title of the puzzle.)